It's hard to say how to improve game scores in general because the requirements of the soundtrack varies so much from game to game. I agree with what Extra Credits said in an episode a while back, that modern game music gets lost in its own bigness and complexity of orchestration, that there needs to be stronger, more memorable usage of melodic phrasing. While strong melodies aren't always necessary - a game soundtrack serves to create atmosphere first and foremost - it leads to many modern OSTs sounding very same-y. Everyone is using more or less the same arrangements, key, and time signature, so without a strong central theme, there's nothing to give a soundtrack definition.
I also kind of wish video game composers would use signatures other than 4/4 more often. You don't need to tap your foot to a battle theme or character motif, so there's really no excuse why there aren't more pieces in 3/4 or 7/8, etc. Most people would agree that the fourth movement of Beethoven's 9th symphony is rousing and energetic, but a good half of it is in 3/4 time. Still, not nearly as important as the first point.
Games are similar to films in this respect at least: proper use of a soundtrack can add a heck of a lot to the emotional impact of a moment, even if the requirements of a game soundtrack are very different of that of a film.