Time travel in Braid

I bought Braid on the promise of lavish visuals and neat puzzles with temporal mechanics, and on this basis I was rewarded. I found some frustration with the controls, which I eventually traced to dodgy keyboard drivers - the game wouldn't register the up or down arrows while I was holding Shift, making it impossible to rewind at high speed. Since I wasn't even aware that you could rewind at high speed, this made one particular puzzle impossible until I eventually caved, broke a long-standing personal rule and looked the answer up online. The game itself, though, is joyous. It's old, I guess, which means either you've played it already or you haven't and never intend to. In the event that you've never played it and can be swayed, I suggest you check it out. Well-judged puzzle difficulty, extraordinary visuals, super desktop wallpaper material, cool new gameplay mechanics, and I discovered some good new music as well. Most of the music in this game is by Jami Sieber, check her out.

I actually severely dislike Mario and Mario games, so this game has that going for it as well.

I don't think I play enough games to be able to say with confidence whether Braid is/was a quantum leap forward for puzzle games or videogames in general. Other than being wonderfully well-executed, the main differentiator for this game is the story, and I really couldn't tell you anything about the story, except that I found each individual paragraph quite hard to swallow. As far as I can tell, Braid's story is deliberately constructed and presented to be super-ambiguous in a way which fosters energetic discussion of possible interpretations. This is a narrative practice which I'm instinctively dubious of. It strikes me as deliberate obfuscation, a way of avoiding stating anything clearly and directly, offloading the author's work to the reader. When I'm invited to lay my own interpretation of events on top of a thing, more often than not I feel an impulse to just step back and give no interpretation.

What I'm saying is that I'm not writing this writeup to cover the text. From my perspective Braid is all about aesthetics, and superbly constructed puzzle scenarios, and mechanics. Braid introduces one new time manipulation mechanic in each of its six worlds. Some of these technically qualify as time travel, some of them don't; some of them have storytelling possibilities, some of them don't. (This is independent of the actual story of Braid, which as far as I can discern is not actually a time travel story at all, although I forgive it.) These possibilities are what I want to focus on here.

Nevertheless: spoilers?


I've written numerous times about time, time travel and time travel in specific works of fiction. One thing I keep coming back around to is the fact that there are models for time travel; in fact, very broad classes of models, which individual time travel stories select among, and then refine for their own specific storytelling purposes. Another topic I've revisited several times, inescapable to any time travel nerd, is that many time travel stories have rough edges or deliberate errors in their models. There will be moments in the story where the strict rules, if there were any, are deliberately disobeyed because they are inconvenient, and because the story needs to go in a different direction from what was previously established to be possible.

This happens because in fiction you can put together whatever sequence of words you like, and nothing can stop you. Your need for one word to follow the other is more important than the need of your universe to be internally consistent. In practical terms, there is nothing which can stop you from making a film whose main conflict is resolved when, say, objects suddenly start to fall up instead of down.

Contrarily, inside a computer game, there are rules. A computer game, like any computer program, can only behave in the way in which it has been programmed to behave. (Give or take hardware faults and solar flares, obviously.) And if you have written your computer program to instantiate and execute a virtual environment, and to allow a player character to navigate that environment, then what you have built is a universe with a model; a model which is inviolate. This is a great way to immediately avert all possibility of inconsistency.

(In The Matrix, while standing inside a virtual combat environment, Morpheus explains to Neo: "It has the same basic rules, rules like gravity. What you must understand is that these rules are no different than the rules of a computer system. Some of them can be bent. Others can be broken." This speech always rubbed me up the wrong way, and not just because it's "different from", not "different than". You can't bend a computer, unless you want to take some kind of science fictional electromagnetic effector to it. A more correct statement would be: "Some of the rules have faulty implementations, which may be exploited. Other rules are correctly implemented but poorly thought out, leaving loopholes." In any case, let's assume the opposite. Yes, Braid may have a rampant buffer overflow which, like The Legend of Zelda: Ocarina of Time, lets you warp directly into the closing credits. But no one's found one yet, so let's assume it doesn't, and that the world the game presents is correctly implemented, not exploitable.)

Braid is a conventional platformer plus a whole slew of time-related game mechanics. Some of these mechanics only dubiously qualify as "time travel". But I can say for sure that all of these mechanics are implemented consistently. To the extent that there is time travel in Braid, and to the extent that the game doesn't just crash when something weird happens, and to the extent that the game isn't loaded with hard-coded one-time special-case exceptions, time travel in Braid is consistent; contradiction-free. This is a good win for time travel fiction!


There's a slight down side to this approach. A game universe, no matter how advanced, is necessarily simpler than the real universe. Braid, like almost every game ever made, does not model air particles, or the real-time propagation of light and sound. The game's collision detection is (is able to be) pleasantly forgiving. Individual breaths of air and blades of grass are not modelled.

So, just because a game presents a consistent model doesn't mean that this model can be transplanted back into "the real world" without contradictions arising. I don't even mean contradictions with the established laws of physics, because unless the world flips upside-down tomorrow and we discover exotic matter, modern physics pretty much conclusively rules out macroscopic time travel. I mean really glaring scientific objections, like, how does Tim's nervous system actually work?

Tim is the name of the player character. Tim/time, get it? Get it?

Of course, a game needn't feature time travel to have these problems. How many games have teleportation? Infinite ammo? Perpetual motion?

2. Time and Forgiveness

The first world, numbered 2 for reasons which become clear later, introduces Braid's core mechanic. This persists through the whole game, and works like this:

  • You can "rewind time". You can travel backwards along your personal lifeline, watching events play out in reverse. You can even rewind time at high speed, or wind forward again if you go too far back, or stall entirely. You continue to perceive normally through this.
  • After rewinding as far as you like, you can let time flow normally again, fully cognisant of everything that happened in all previous timelines.
  • You can use your foreknowledge to do something different from what you did before.
  • Get-out clause: if you die, time stops, and you can/must rewind to save yourself.

This has some interesting consequences. As the game designer, you don't need restart points, a save system, lives or health anymore. You can just rely on the player to rewind time any time they make a mistake, such as falling into flaming spikes. If a situation turns out to be thoroughly doomed and inescapable, they can simply rewind further, all the way to the beginning of the level if need be.

If the player forgets something, they can wind back and get it. Say, if there's a gap which can only be crossed by bouncing on an enemy from high above, but they already killed that enemy, they can wind back and deliberately leave it alive when they pass it in the next timeline. There's a micro-puzzle, right there.

And if a particular obstacle can only be overcome with precision jumping, and there's a near-bottomless pit below or a risk of instant death from a hundred fireballs, you-the-game-designer can make that task unusually difficult and unfair, because if the player screws it up it only takes a second to rewind the entire scene and try again with slightly different timing.

So, these are puzzles and challenges. Fairly basic stuff, and this mechanic alone only sustains one brief world. Are there also stories that can be told with this mechanic? Of course. For a character to be apparently unkillable, supernaturally well-prepared, and a supernaturally lucky guesser, is a legitimate superpower. The scope of applications ranges from winning coin tosses, to always choosing the perfect words in every important conversation, to never missing a shot with any kind of firearm.

As with many time travel models, this ability is so powerful it probably needs to be toned down before it becomes practical for a story. Some things to explore: the sheer boredom of constantly experiencing the same day or hour or minute over and over again until you get it right; the discontinuity when you "resume" after rewinding time a little; the agony of experiencing the same unpleasant fight over and over again until you win. There are also deep paradoxes which arise when one character with this power runs into another character with the same power. What does this person perceive when you rewind time, and vice versa? In a fight between you, who wins? How far back can you go? How much of your life are you willing to unravel and experience again just for the sake of a particular confrontation? How much of your life would you simply go back and re-experience over and over again?

The more I think about this, the more I think I need to write it. Although, I can't imagine nobody has written it already.

3. Time and Mystery

In the second world, the time-reversal phenomenon remains, but new rules are added.

  • Luminous green objects are not subject to your time-reversal power. They always behave normally, whether you are winding time forward or backward, or even while you are dead and time has apparently frozen.
  • When you rewind time, you travel backwards along your established historic track, all the way to the level entrance at the beginning of time. This remains the case even if (1) a green platform now presents an obstruction which was not there in the original timeline (you will rewind straight through it) or (2) a green platform which you used to reach a certain area is missing in this timeline (you will appear to run across thin air).
  • If you unfreeze time while you're inside an obstacle, you'll probably die. If you unfreeze while running across air, you'll fall.
  • Some green platforms are "contagious". While you are standing on one, you become green, and therefore immune to your own time-reversal power. This essentially erases your past history. You can rewind all the way to the beginning of time, with the whole universe at first positions, but you'll still be on the platform, instead of at the level entrance.

Green objects break "history", if there ever was such a thing. Green objects force us to accept that the universe of Braid has at least two time dimensions. This is the only way in which a green object can obey "forwards" physics while the universe is rewinding around it. (Psst. In fact, this has always been the case since world 2. Notice how you, the player at the computer, are also glowing green?)

What happens when a game designer starts playing with these rules? There's no point in me going over that because what happens is almost exactly this game, starting with this world and then every world after it. Each individual jigsaw puzzle piece puzzle (?) explores a distinct ramification, starting with The Pit and finishing with the boss, whose health is persistent across multiple timelines and who is defeated by dropping the same single chandelier on his head five times in five timelines.

There is a synergy, some kind of weird -morphism, between science fiction stories and puzzle games. In I, Robot, Isaac Asimov invents Three Laws of Robotics, then uses them in various combinations and variants to generate a wide slew of different short stories. It's a technique with very broad applications. You spin up a new law of physics or a new MacGuffin and then think, "What if? What are the consequences of this rule or object existing? How does the universe change? How must the universe change retroactively to allow this thing to exist in the first place?" Then you turn the handle until a story appears. I've done this myself numerous times, particularly with time travel stories. As you go through my fiction archive in reverse order, it becomes increasingly blatant.

Meanwhile: you, the game designer, are building a puzzle game. You develop a new mechanic or a small pool of new mechanics, and you implement a game universe where these rules are law. Then you start toying with what you've built, discovering the brain-swivelling results. Then you develop puzzles such that each individual brain-swivelling result is the solution to a puzzle.

Obviously now I have to skew sideways into the vast list of reasons why these two tasks are actually totally unlike one another. Such as the fact that the purpose of a puzzle is to be impassable until the player thinks and then solves it, earning that spark of achievement... whereas the purpose of a story may be to cultivate literally any imaginable reaction, but whatever happens, you can never stop a reader from reading all the way to the end.

But some science fiction stories really are just little puzzles, some of them (Asimov) really do just start with a wacky concept as a setup and conclude with a wacky consequence as the punchline. And there's something to be said for what I guess I'd call economy of invention when worldbuilding.

Getting back on topic, can this "green" stuff be turned into stories? I mean, stories which are more substantial than literal retellings of the events of some random individual playing Braid? Well, possibly. I mentioned above that you'd need to tone down the time-rewinding power in order to make it less universe-endingly powerful. Introducing special entities which are simply immune to that power is a great start. The boss I mentioned is actually the concept with the most obvious potential here. An alarming development: "I see what you're doing, protagonist! You can't hyper-prepare your way out of this one. I'm coming for you!"


"Time and Mystery" is also the world where we start to run into paradoxes. To be explicit about what I mean here, a paradox is a scenario which apparently involves a contradiction, but actually does not. Paradoxes are completely standard fare for time travel stories. Seen from the perspective of a time-locked, non-green Goomba, the Braid universe is highly paradoxical in nature. Tim somehow enters the level from a contagious green platform instead of via the level entrance; Tim apparently runs across platforms which only existed in a previous timeline; jigsaw pieces disappear spontaneously, collected by Tims in prior timelines.

None of this is actually problematic. Real contradictions would be problematic-- in fact, contradictions are highly undesirable in almost all kinds of story. The real physical world, almost by definition, does not contain contradictions, and ideally the same should be true of model universes constructed for fiction. But computer games, being both necessarily simpler than the real world and physically embedded in the real world, do not contain contradictions, except arguably when they crash. The Braid universe is highly paradoxical from most perspectives, but the game itself isn't famed for its instability. It behaves consistently, and does not contain contradictions. This makes it fair to set puzzles in this universe, and it ensures that these puzzles are solvable through rational thought.

4. Time and Place

In the third world we get another new rule. Tim continues to behave as before, with rewindable time. Green glowing objects are, as always, exempt from all time shenanigans and operate normally. But:

  • The game level, including all Goombas, cannons, clouds, levers and platforms, is operating on a third time axis, one which is connected to Tim's X-position in the level.
  • As Tim moves from left to right, events unfold according to what essentially amounts to a script. Tim can interfere with the script, by bopping Goombas and throwing switches.
  • As Tim moves back from right to left, even if by a different route, events fold back up again, Goombas unbop and switches unthrow.
  • Objects experiencing "backwards" physics (i.e. the game level, as Tim progresses from right to left) do not interact with objects experiencing "forwards" physics. For example, Tim cannot bop a Goomba while moving left, because this makes no causal sense.

The aim of the puzzles in this world, broadly, is to engineer a sequence of events, from left to right, which leaves you with all the jigsaw puzzle pieces you need. Instead of a "live" scene which is constantly playing out in time, the game level is more of a dynamic maze which you must navigate. History is almost a physical object laid out in front of you, with which you interfere until you get your way.

(It turns out that the behaviour of ordinary, non-green keys under these circumstances is truly bizarre, bizarre enough to warrant a whole level ("Fickle Companion") dedicated to exploring this behaviour. I have a hunch that this behaviour was not coded in deliberately; rather, the world's rules were programmed, and then this astonishing behaviour was discovered as an emergent property, after which puzzles were built around it. Under normal circumstances, the key sits still. Carrying a key from left to right, it follows your hand, as normal. Move from right to left, though, and the key rewinds along its personal timeline instead of following your path back across the level. The key jumps back up to a platform you fell from, and then instantly descends a vertical ladder which you climbed, with an unnerving visible discontinuity. However, a green Goomba can carry the key from right to left with impunity, effectively unwinding and rewriting part of the key's past history, placing it in the "past" at a place where it could never be put any other way. You can then retrieve it from this location in the past and carry it forward along different paths which were otherwise unreachable.)

Overall, as I think you can see, "Time and Place" its multiple time dimensions are quite hard to explain on paper. As complex as these rules are, they are far easier to understand when presented as an interactive game. If you're reading this essay having never played Braid, I dread to think how difficult it is to understand the paragraphs above.

Because of this I have difficulty imagining how you could convert this world or model into a coherent science fiction story. I guess the lesson is that some things are just better experienced interactively than any other way. Some models/mechanics/concepts are so convoluted that a game is really the only sensible way to explain or experience them.

I've run into this before. For example, I was tempted to try to make a game, or at least a demo, out of this absurdly complicated model. I didn't do it, as didn't think the model had enough value to be worth exploring that far. But I'm still sorely tempted to do this for Primer, just because it would make the whole film so much more accessible for the confused. And I think there might be a neat game in there.

Some models/mechanics/concepts, of course, are so sophisticated that even a correctly-programmed game can't help much. Among these models, alas, is real physics. Bad luck, everybody. We live in one of the bad universes.

5. Time and Decision

The fourth world drops the zoetrope-esque behaviour of "Time and Place" and replaces it with:

  • You can see a shadow of the previous timeline. If you rewind time and do something else, you can watch a shadow of yourself carry out the same acts you just rewound - along with an entire shadow rest-of-the-world, including shadow cannons and Goombas.
  • Once the shadow universe's prescribed sequence of events runs out - because player input ends, because you hit rewind - this shadow universe continues moving until it eventually fades. Even the shadow version of Tim continues moving until he comes to rest.
  • All of which is absolutely useless without this extra note: objects which glow pink are present in both timelines. They interact with both the shadow universe and the present universe.

This leads to puzzles where you have to cooperate with your shadow self to get things done - and frequently, sacrifice your shadow self. This is obviously a potent storytelling concept with hooks both neat and grisly, although it can be executed very easily without invoking time travel, and indeed has been, numerous times. Just off the top of my head, you could go and look up the film The Prestige, or any X-Men story involving the character Madrox the Multiple Man.

6. Hesitance

The fifth world introduces a movement-slowing ring, which yields clever new platform puzzles. Unforgiving as these puzzles are (thanks to the still-present rewind mechanic), this isn't time travel by any stretch. In fact, time distortion of this kind is a genuine phenomenon in the real world, displayed by extremely massive objects and fully explained by the general theory of relativity. Possibly acknowledging this, "Time and" is missing from the world name.

I'm hurrying because the good bit is next.


The sixth and final world, "1.", is telegraphed since the beginning of the game. This is the one where the logic starts to get laugh-out-loud smart. In this world, game universe time apparently runs backwards. Goombas rise, dead, from the bottom of the screen, collide with flames which bring them back to life, and are sucked back into cannons.

Most jaw-droppingly, if you bop (or rather, unbop) a Goomba as it rises up from the bottom of the screen, you can retcon its death from death-by-flame to death-by-bop. This also retcons the Goomba's origin to a different cannon. You've switched it over to a different possible past!

I want to say that solving the first(/last) puzzle of this world was the most joyous moment in this whole game for me.

This game mechanic is absurdly easy to get wrong. After a little observation and study, it becomes clear that the game can't possibly be implementing the laws of physics in reverse somehow, because in the temporal universe in which we live this is actually impossible. Nor is there a pre-existing game history which is being rewound. Instead, the game is programmed to behave in a way which, when wound forward again, appears realistic. When a Goomba gets near a cannon, for example, it starts bouncing in such a way as to take it into the cannon's mouth, while the cannon's fuse withers to black. When the cannon swallows the Goomba, the fuse ignites and fills back up.

This takes a lot of care, and you can see that the puzzles in the first three levels of this world are very tightly constrained in order to avoid exposing the "scaffolding" which makes it possible. Green objects and mobile platforms are absent, for example, because they'd cause all kinds of causality problems. Not that it would be impossible to deal with them, consistently, even, but the conceit of backwards physics would be violated.

(Can you imagine trying to build a game with combat under these circumstances? Every time the enemy hits you, you gain health... What happens if you're hit while at full health? The universe explodes? I'm given to understand that all of Braid was originally intended to work in this way, but the concept was dropped when it turned out to be too difficult to do. Considering what the Braid team did manage to do, this is an alarming statement.)

In fact, there is at least one visible slip-up. In the climactic final section of this world (and the game), there is a cannon which is constantly sucking in fireballs, which are flung at it spontaneously by a far wall. The far wall continues to fling fireballs up to and after the point where the cannon is swallowed by the moving wall of flame. When this happens, the backwards-travelling fireball, having no coherent past history track, simply halts in mid-air and disappears. A more advanced game would have to look into the realtime future of the game level, determine whether the cannon was going to still exist for long enough, then use this to decide whether the wall should produce a new fireball or not.

And yet... fireballs don't disappear accidentally. Somebody discovered this issue and had to code that code path to make it happen. Remember what I said about hard-coded one-time special-case exceptions?

In summary, causality is really, really hard to do without. I know of only one other work of fiction which uses this model, the Red Dwarf episode "Backwards", but it, like that whole show, leans heavily on comedy to hide inconsistencies. Which is a totally legitimate way to play it, and possibly the only way to play it.


In the final section of the main game, Tim runs through a tunnel pursued by fire, while the princess - who, and I'm just mentioning this because I want to make sure I'm not crazy, does not have a braid in her hair - pulls levers to help him progress. As Tim reaches the princess's bedroom, time suddenly reverses, and the whole level plays out backwards. Viewed in reverse, it becomes clear that in fact the princess is fleeing from Tim, pulling levers to try to trap him. You thought the princess had escaped from a villainous knight; actually, she was rescued by him.


This is actually no great narrative trick.

Alright, I admit it. It's genuinely brilliant, and effective, and it's a knock-out climax to the game. Whether it illuminates the story any, I don't want to try to say. But at the time I played it, I was super impressed.

But a while after I finished Braid I suddenly realised that I'd played this game before. The game of reversing a story, I mean. We did this with films.

The Matrix: Neo, the One, the most anomalously powerful human in the Matrix, fights and is trounced by a particularly dangerous agent of the system, Smith. Although Neo recovers, his psyche is so damaged that he loses his reality-shaping abilities and then his basic combat skills. He becomes gradually weaker and less confident; eventually, useless. The crew of the Nebuchadnezzar reluctantly plugs him into the Matrix, essentially turning him over to Smith, to live a dismal life out as an insensate drone. Neo is left with nothing but a grey cubicle job and a nagging suspicion that something is wrong with the world. Humanity, meanwhile, is doomed without their saviour.

Toy Story: Arriving at their new home, Woody and Buzz immediately head next door and execute an elaborate prank on their new neighbour kid, Sid. It turns sour when Sid captures them, torturing Buzz to the extent that he loses his mind and begins hallucinating that he is a real space ranger. Somehow they escape alive, but Buzz is never the same again; eventually, his owner, Andy, gives him away. And the other toys forget he ever existed.

Reversing the order of events of a story almost always totally alters its meaning. Naturally! This shouldn't be a surprising discovery. Stories have arcs. They have structure, and finish up in a different place from where they started. Stories with perfect symmetry - palindromes - are very rare, and have to be deliberately constructed to be so.

And notice how much "fuzz" I used in my two examples. Naively running a film backwards doesn't work; listening to human speech backwards doesn't yield meaningful words. Of course, I had to reverse the films thematically, using broad strokes.

Now go and play that final level, which is called "Braid", again. Notice how the princess pulls unnecessary extra levers, both on the first pass and the second. There are ladders on the second pass, which Tim should have been able to climb, but they weren't there on the first pass. Tim leaps up to platforms he should not be able to reach. The dialogue is delivered in a different colour, conveying a different tone of voice. Even the princess's facial expression as she's rescued is different from in the intro.

"Braid" is fuzzed, too. Because that's the only way to make a story read coherently backwards as well as forwards. Recontextualising a story to give it a whole new meaning is legitimate - but recontextualising it by not somehow accidentally reading it backwards? This is the dictionary definition of the word "contrived".


In the epilogue, I see that there is still no princess, and Tim has built a castle of his own out of his experiences. And what have we learned?

Implementing a game can help you, the implementer, turn an ill-defined or inconsistent concept into something concrete.

A small pool of rules can yield huge storytelling possibilities - but you've got to do some exploring to find them. A game is an excellent tool for this exploration. You may discover things you originally had no idea could be possible.

Playing a game can make a complex concept easy to explore and understand. Some concepts are so advanced that they can't be understood any other way. Some concepts are far too advanced for their own good.

No matter what your chosen medium, no matter whether highly advanced time travel is involved, or just a guy jumping from platform to platform, successfully executing on an idea takes an insane amount of hard thought and hard work.

And you're still going to make mistakes, and nerds like me are still going to jump all over you for it, because that's how I entertain myself, because the real universe is terrible.

I had a great time with Braid and it looks like I have new projects as a result. Good stuff, five stars.

Discussion (27)

2015-03-04 00:51:31 by ToaKraka:

"The more I think about this, the more I think I need to write it. Although, I can't imagine nobody has written it already."<br/><br/>The protagonist of the movie "Next" has a time-rewinding power--but, there, it's limited to a maximum duration of two minutes.<br/><br/>Also--some time ago, I read a Naruto fanfiction story with the same name (ID number 4202377 on fanfiction dot net) in which the protagonist had this same power. The story was incomplete; however, it had an extremely moving scene (in chapter 7), in which the heretofore-undefeated protagonist swaggered confidently into a fight with an enemy far above his level, and then was frozen to the spot with horror as he was hit with memories of dozens or hundreds of deaths less than two minutes into the future--even with infinite rewinds, the opponent was so much stronger than the protagonist that it seemed the protagonist simply couldn't win.

2015-03-04 03:16:06 by GAZZA:

OK, sold. $10 on Steam, for all that? Got to be worth a look. Oh, by the way, there's a free demo there as well.

2015-03-04 04:20:04 by T:

Loved the entire article - I like this time travel mechanic series - but one detail from the introductory section stuck out at me as well. I don't think I've ever seen anyone call out Braid's story on not being about time travel. Now that I've seen it pointed out, it feels very bizarre to me. Also to other skimming the comments: I second the recommendation to simply play it to learn the mechanics. Much like SpaceChem, you can almost feel your mind contorting and expanding to internalize the concepts presented.

2015-03-04 09:45:04 by Toph:

>Can you imagine trying to build a game with combat under these circumstances? Every time the enemy hits you, you gain health... What happens if you're hit while at full health? The universe explodes? Yes. That seems to be the only way for a game like this to make sense: if you reach a state with no consistent past, you lose the game. Of course, you also can't actually be killed, so the game still needs a failure state. How neat! <i><a href="http://www.alkemi-games.com/tfp/">Thanks For Playing</a></i> works like this.

2015-03-04 13:00:24 by john:

You missed the stars, and the alternate ending. Tim can't rewind beyond the beginning of a level, and is on a quest to repair the mistake he made immediately before the beginning of, or rather after the ending of, level 1. One of the stars becomes impossible to collect after the level 2 puzzle is assembled, because you need to misarrange the pieces while you're in the house in a way that provides a platform. Yes, that's right. There's a mission-critical puzzle on what initially appears to be just the level select screen.

2015-03-04 14:13:08 by wfn:

In a mostly unrelated OT note, here's a paper showing that Braid mechanics are Turing-complete, and that therefore Braid is undecidable (this probably applies to a rather wide range of games, of course): http://arxiv.org/abs/1412.0784

2015-03-04 15:58:49 by Voidhawk:

>There are also deep paradoxes which arise when one character with this power runs into another character with the same power. >The more I think about this, the more I think I need to write it. Although, I can't imagine nobody has written it already. The book you're looking for is one I would love to hear your review of: "The First Fifteen Lives of Harry August" by Claire North. Harry August lives and dies normally, then wakes up in his younger body with all his previous memories. There are other people who have the same ability. It gets... complicated.

2015-03-04 16:25:40 by gwern:

> There are also deep paradoxes which arise when one character with this power runs into another character with the same power. What does this person perceive when you rewind time, and vice versa? In a fight between you, who wins? How far back can you go? How much of your life are you willing to unravel and experience again just for the sake of a particular confrontation? How much of your life would you simply go back and re-experience over and over again? The more I think about this, the more I think I need to write it. Although, I can't imagine nobody has written it already. To chime in: the light novel _Utsuro no Hako to Zero no Maria_ ("The Empty Box and The Zeroth Maria") deals with this and some related issues. _Primer_ might also deal with that... I think. (Who knows?)

2015-03-04 17:26:57 by Toph:

Come to think of it, World 1 is strange because Braid has already established mechanics for time-reversed objects interacting with one another, and World 1 breaks them. The rule is simple: Objects moving backwards in time do not interact with anything. They teleport to the state they were in in the "previous" moment, even if that state is now halfway across the level and inside a wall. They can affect object moving forward, but are not affected by them. For example, in World 4, Tim can bounce off a time-reversed enemy without harming it. And a green enemy can bounce off Tim while he's rewinding. World 1 works by completely different rules to what we've had so far. Luckily, there aren't any complex puzzles in it, even the final level is mostly challenges of timing and reflexes, so the player doesn't have to re-learn everything five minutes before the final exam. But it would have been so much more elegant if it could be made to work within the established rules.

2015-03-04 20:43:06 by Foxfire:

> In summary, causality is really, really hard to do without. > I know of only one other work of fiction which uses this > model, the Red Dwarf episode "Backwards" _The Arrows of Time_, the third book of Greg Egan's _Orthogonal_ trilogy, features characters interacting with a world whose arrow of time runs backwards compared to their own. This results in scenarios where the "preexisting" state of the world telegraphs their own possible futures- footprints that someone will eventually un-step, dust that follows behind the broom instead of in front, etc. >There are also deep paradoxes which arise when one > character with this power runs into another character > with the same power. >The more I think about this, the more I think I need to > write it. Although, I can't imagine nobody has written it > already. Brandon Sanderson deals with something like this in _Mistborn_, although the rewind/prediction ability is limited in temporal extent. The serial novel _Worm_ (https://parahumans.wordpress.com/table-of-contents/) also features a character with this power, though I don't recall him interacting with someone else who also has it. His version is limited by the number of concurrent timelines he can explore between "savepoints".

2015-03-05 15:07:07 by Anonymous:

When I played this it was in one sitting with a friend over the course of one long night. After we were done we didn't have enough yet, so we blew each other's minds by trying to work out a multiplayer version and then went to sleep. A night well spent.

2015-03-06 16:09:36 by Aegeus:

Achron is the only game I know of that has multiplayer time-reversal. It handles this by making it cost "chronoenergy" to change the past, which means you can't just rewind and repeat forever - eventually one of you will run out of energy and have to accept the timeline as it stands. It also makes changes to the timeline propagate slowly through "time waves," giving you a chance to react to the changes. If you deliberately cause a paradox, the world will oscillate back and forth between two possible states until it reaches the "unplayable past," where the timeline becomes fixed in whatever state it ended in. This will probably leave an inconsistency in the timeline, like a unit created from a factory that was never built, but it's better than a paradox destroying the universe.

2015-03-06 18:45:18 by Jymbob :

"Good stuff. Five stars. I'd have to check, but I believe there are seven.

2015-03-06 23:56:25 by warlock:

The best way to play Braid - which may neatly sidestep your keyboard issues - is with a gamepad & a little utility called Joy2Key, which binds joystick buttons to keyboard presses.

2015-03-07 00:17:55 by DanielLC:

Achron is an interesting multiplayer game with time travel. I have played two games that were basic platformers, but running backwards. The paradox avoidance in them was simple: if there's a paradox, you lose. This caused some weird things, like you're only allowed to pass through a space containing a coin once.

2015-03-08 00:13:07 by Black Noise:

Ah nostalgia. One of the more fun puzzle games from when I had time for them. On a completely* unrelated note, the manga "Purple Qualia" has very analysis-friendly physics. *almost, hard to explain more without spoiling more than this sentence already does.

2015-03-09 18:24:14 by P:

Dear Sam, one of my 12 year old pupils asked today "but what is time?". Could you give her some sort of answer, I couldn't. Cheers Mr P

2015-03-09 20:26:21 by qntm:

Leaving aside the high philosophy, I'm going to say that time is the thing which separates yesterday's lesson from today's lesson.

2015-03-09 22:21:13 by infz:

Disappointed you didn't chime in on the alternate narrative presented by the alternate ending.

2015-03-10 20:11:00 by salty-horse:

Jonathan Blow, the creator of Braid, gave a talk in which he describes the idea of designing by starting with a basic mechanic - a consistent model - and exploring it to find interesting concepts and puzzles to challenge the player, and guide their own exploration. "Jonathan Blow & Marc Ten Boch, Designing the Universe, October 7th, 2011." https://www.youtube.com/watch?v=OGSeLSmOALU The talk is also given by Marc ten Bosch, who's also working on an interesting game: Miegakure. It's a 3D game, but you can travel along a 4th dimension by "rotating" the view. Like Braid, it takes a model, and explores what that means through interesting challenges. The official website is here: http://miegakure.com/ And here's an interview by Computerphile: https://www.youtube.com/watch?v=da5RoS4w5YU

2015-03-10 23:35:22 by Dan Hite:

Roger Zelazny used the time altering concept of Temporal Fugue as a combat mechanic/superpower in his novel Creatures of Light and Darkness (which I read decades ago so it likely precedes many of the other interesting references people have helpfully given here). I like the TV tropes C of L&D entry (as opposed to Wikipedia) as backgrounder simply because the "tropes" exploration there fits in with the tone of your Braid exploration here... http://tvtropes.org/pmwiki/pmwiki.php/Literature/CreaturesOfLightAndDarkness

2015-04-04 05:23:47 by David DeLaney:

And the webcomic Skin Horse (from the same people who gave us Narbonic) devoted an entire chapter to a young man who found himself inexplicably possessed of a 'save point' in the middle of an attempt to infiltrate $Evil_Company with a friend; the chapter is titled, unsurprisingly maybe, "Choose". --Dave

2015-08-31 17:46:49 by Tyr:

One interesting thing to note when looking at a broader universe in which Tims rewind powers exist, is that Tim is ultimately the bringer of the apocalypse. We don't know how far reaching this power is, but even if it is only limited in range to this world or this star system, time literally runs out a few decades after the game is set, at the end of Tims natural lifespan. This could be a fascinating subject for a story (and you are welcome to steal it, I'm no author). Our cursed hero spends a while having fun with his rewind powers, dies a few times, and then, when sitting, paused after a surprising death, realises that without him, the world will never move on, and the entire human race is trapped within the tiny bubble of time that, for whatever unknown reason, it contingent on his life and continued existence. This thought then becomes his motivation for the rest of the story, and drives him to research more and more elaborate ways to prolong his life. Others around him think that his wish to live forever is selfish, or born out of fear of death, when in fact it is born out of a need for the species as a whole to continue. The ending could go one of three ways, as I see it. Either he finds some miracle of science that can keep him alive indefinitely, which might be a great sacrifice for him such as a painful stasis chamber or living-death. Or he resolves that it is not possible and accepts that the fate of mankind is to end with him, but be reborn each time he rewinds, which he can seemingly do forever. Or the third option is one used in one of the various endings of the Butterfly Effect (spoilers follow); that he rewinds so far as to never have been born, thus allowing time to move on with nobody having that power. Just an idea I had, reading this. Thank you for the inspiration, and as I said, if anybody wants to pick up these ideas and turn them into anything at all, feel free. (cc0)

2015-09-18 16:09:28 by Turgid:

Re: characters with the time rewind power. Groundhog Day inspired All You Need Is Kill inspired Edge of Tomorrow, the latter two of which hint at the rewind battle between the villain and the hero. Forked somewhere off that line, a great short film called Rope A Dope - Wake, Fight, Repeat is available on Youtube that starts out like a straight Groundhog Day scenario but with more kung fu comedy. But they kick it up a notch in Rope A Dope 2 which introduces a villain with the exact same power, and how they go back and forth in amusing fashion. Go watch it for free!

2017-03-29 12:01:03 by madblade:

"[...] the game can't possibly be implementing the laws of physics in reverse somehow, because in the temporal universe in which we live this is actually impossible." Only intuitively [1]. In most models (except for thermodynamics and utterly arcane cosmology stuff), equations of physics are time-reversible [2], i.e. they behave exactly the same forwards and backwards. Think of the solar system: there is nothing in classical (even relativist) equations that tell us whether planets should revolve clockwise or counter-clockwise around the sun. [1] https://www.perimeterinstitute.ca/videos/time-reborn [2] http://www.cornell.edu/video/richard-feynman-messenger-lecture-5-distinction-past-future

2017-04-10 09:51:35 by CODEMON:

Nice explaination. Looking at the story, it looks like the game is trying to give a deeper message about the nature of time. 1. Tim is time without e 2. Tim's facial expressions are those of happiness when he is moving(time doesn't stop) 3. One of the books has a sentence saying "tim needed to be non manipulable" ( we can't manipulate time) What do you think the devs are trying to emply with this game?

2021-02-10 08:14:13 by matthias_code:

I still want to get into Achron, afaik the only time-travel strategy game. In there you can see the game in a timeline, rewind and fast forward, and spend currency to time-travel units to specific points of a match to undo actions by others.The time-travel is _highly_ fascinating, but the only issue is that the game around it itself isn't that interesting

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