Weirdly I remember around 1998 I think I was waiting on a game called PREY that sounded awesome with an original idea concerning portals..etc..
It got put on hold and finally the game came out a few years ago and it kicked ass! Even though it's not used in the exact same way Prey should be given props for doing the whole portal thing before Portal. Not to mention the game is just plain out FUN with cool environments. I really miss games like that. Hopefully with Duke Nukem coming out ..etc...it will change things from this whole realistic shooter thing.