it would be brilliant to see it become reality, but unfortunately, as mentioned they just don't deliver the story as well as the game itself, uwe boll isn't fantastic and he's butchered many films but for what it's worth he did a fair job with resident evil. as much as i'm a huge fan of the game series prior to 5 of course the movies weren't horrible, not amazing, but not horrible.
and also with the postal movie he delivered on some of the fans favourite game references but all in all not a fantastic movie, but at this time we have michael bay, the cg mad explosion vomiting madman that created the transformers movie, which once again wasn't great but wasn't awful.
we have uwe boll as mentioned above, and a few more names like alexandre aja, who aren't fantastic but once again make watchable movies, i think something like half-life is so well made and the story is so rich that the best way to get it across is in game form, same with world of warcraft and other blizzard titles *stares lovingly at starcraft* there is a lot of lore and back story which was told through the medium of games and books working fantastically, but because of this its a fair enough guess that they just wouldn't deliver as a movie.
its not true with lets say the lord of the rings movies book to movie is sometimes workable.
but all in all it only worked because peter jackson was a fan of lord of the rings, if somehow a director who enjoyed half-life teamed up with valve to work on a film as team then we would probably have a fantastic film. But the chances are rather slim and the budget would have to be immense so its probably a long shot unless valve release their own set of cgi movies maybe 30mins in length to tell the story part by part, kinda like the games that would work.
i do apologize for the essay, just a subject i find interesting
also other things that would make a fantastic movie/movie series....
Warhammer universe 40k and warhammer fantasy.
Elder scrolls series would be fantastic.
even fear could make a half decent movie.
just my opinion anyhow