When it comes to videogames I don't think that a good story-line is as big of a motivating factor as some people assume ... If you read the list of the top 50 games from any given year you will see the vast majority of games have pretty marginal story lines, and the games that have good stories (by videogame standards) also have good gameplay which could be argued is the real selling feature of these games.
People choose to play videogames because they're interactive, and it is impossible to tell a good story that is interactive. You can offer a good setting in an interactive way, and you can introduce good characters in an interactive way, but a story implies plot which requires a protagonist, their conflict and the choices they make. In a videogame you are the protagonist and any choice that can be made is yours to make which causes problems for telling a decent story; suppose for a moment that I decided that I didn't want to be a eurotrash low-life criminal and I decided that I wanted to open up a flower shop instead, how can you (as an author) anticipate this choice and work it into a game like Grand Theft Auto 4? We see this limitation in every videogame that trys to allow choice, and your choices are always limited and have a very minimal impact on the story (except for the end cinematics).
