cordeos said:
Wow... you beat me to the point. Those are two that often get overlooked. For me there is a list of several games that I would say are revolutionary.
Prey - for the aforementioned gravity inversion and spirit realm
Red Faction - the environments that were 90% destructable.
Halo - for all of its detriments, it has to be the most polished game in history
Ghost Recon - nothing like playing deathmatches where 1 hit usually kills you from a handgun
Doom - for starting it all
Duke Nukem 3D - for making the character you play cool
Goldeneye/Perfect Dark - for bringing the genre successfully to the consoles
Timesplitters - for its friendly level editor, frantic pace, and humour
Unreal Tournament - alternate fire that matters
Half-Life 2 - gravity gun, 'nuff said
System Shock 2/Bioshock - being able to have a quality game with a unique story
Breakdown - to my knowledge, the first successful venture to a first person game where there is more interaction than just 'see enemy, shoot enemy'
Mirror's Edge - for attempting something crazy and having a lot of fun with it
Portal - how can you not think it's cool?
Turok - A bow and arrow... in 1997... on a console... with real physics that caused the arrow to lose height during flight.... brilliant
Thief - First person stealth with a bow and arrow... awesome!
I think I have covered everything I thought added something to the genre. Toodles!