Movies are on rails. Videogames are open-ended

The problem with making the transition from a movie to a videogame or in the opposite direction is that of freedom. Movies are on rails. Videogames are open-ended. In movies the hero makes all his own decisions. In the videogame YOU make those decisions. Thus, something is lost in either transition.

The reason so many movies-from-videogames suck is that videogame universes are only designed to be good universes to play videogames in. The Mortal Kombat universe was just a backdrop for a lot of one-on-one fights, for example. Doom is a good universe for scary darkness and fighting evil things. Neither of these are good universes for STORY, and for CHARACTER, because these aren't the things traditionally valued in a videogame experience.

Exceptions (and therefore things which could make great movies if handled properly) include Halo, Deus Ex, and little else...