So what's your one single favourite game for each console or operating system? Think the game that you'd have inserted in your console at all times, or for some bizarre reason, the only game you'd have installed on your computer.
Here are mine
Computer:
DOS - Wing Commander: Privateer Gold - the game ended a bit too soon, but that was because I wanted to play it much, much more. The gameplay works well, the story is good, and some of the characters I actually ended up caring about.
Windows 98 - Deus Ex - this shouldn't come as much of a surprise, it has RPG elements, which I absolutely love, stealth elements, which I absolutely love, and great FPS gameplay, which I absolutely love. Oh yeah, it's also cyberpunk, which I love.
Windows XP - Unreal Tournament 2004 - UT99 almost made it in for Windows 98, but 2004 takes everything good about it, and either keeps it or makes it better. The single player mode with selecting a team and earning credits is also pretty sweet.
Windows 7 - I haven't decided yet, plus it's rather hard with new games coming out this year that I'm very, very interested in.
MacOS Classic 68k (System 7.5) - Escape Velocity - EV Nova is good, and servicable for Windows, but I feel the original is still the best, somehow they just got it right on the first try, plus captain hector is just a little less annoying
MacOS Classic PowerPC (System 9) - Nanosaur - it's just a plain good game, and actually creative as far as shooters go. I also know a couple people who bought an iMac just for this game. I don't think I'd ever get tired of it.
OS X - Bubble Trouble X - kinda cheating since it's a remake from Classic, but I picked EV earlier, and could have done EV Nova here.
BeOS 5 - can't remember the name of it, but that one RPG that came with the install was pretty fun
Home Console
NES - Crystalis - I really dislike Zelda, but Crystalis worked quite well, good gameplay, interesting story, actual character advancement more reminiscent of a well fleshed out RPG instead of Zelda's symplistic heart boxes.
SNES - Super Mario All Stars - kinda cheating to pick a compilation, but there isn't a single SNES game that stands out to me as one I really want to keep playing
N64 - Rogue Squadron - haven't played many N64 games, but that's the only one I really enjoyed.
GameCube - Mario Kart Double Dash - the gameplay is unique among Mario Kart games, being able to have two players on the same Kart is pretty sweet, and also helps out for party games where one person might not be a great driver but can still have fun shooting powerups.
Wii - generation isn't finished, and I'm still finding new games for it, plus Xenoblade might get ported.
Master System - Ecco The Dolphin - it originally came out on Genesis, but that's gonna be taken up, and I never actually played SMS
Genesis - Ristar - still one of my favourite games of all time, and it disappoints me that it played a back seat to Sonic. Of course Ristar may have been butchered as badly as Sonic otherwise
Saturn - I had one, didn't find a single game I liked, but I never got my hands on Sturn Bomberman, so that.
Dreamcast - still haven't got my hands on one. Eventually though.
Neo-Geo - same, although it's probably easy to go to Metal Slug or KoF with it.
PlayStation - Final Fantasy VIII - pretty much every other PlayStation game I've played has been updated and has better gameplay on a newer console. FFVIII is pretty unique, and to this date still hasn't been redone. Also one of my favourite Final Fantasy Stories.
PlayStation 2 - Persona 3 FES - managed to dethrone Final Fantasy X for me and set a new bar for immersive storytelling RPGs
PlayStation 3 - it's probably cheating to put Little Big Planet 2 in before I've even played it, but with user generated content it's something like 20 games in 1.
Xbox - Baldur's Gate Dark Alliance - my PS2 and GameCube slots were already taken up, while I like the GB story, the mechanics sucked. Dark Alliance re-did them and does Diablo better than Diablo, while doing BG better than BG.
Xbox 360 - Bayonetta - Dead Rising is fun and unique, but Bayonetta is a finely crafted beat-em up, and there'll be endless replay value trying to eventually get straight pure platinums on the hardest difficulty.
Commodore 64 - Great Giana Sisters - I'm relying on nostalgia here, but Chris Hüllsbeck made a great soundtrack too
Handhelds
GameBoy - Super Mario Land - perfect gameplay, perfect and varied level design, great music. I never get tired of playing it
GameBoy Color - Dragonball Z Legendary Super Warriors - I really wanted to put Super Mario Land 2 in here, but that would be cheating. GBC was a low point in my opinion
GameBoy Advance - Kirby and the Amazing Mirror - any Kirby game would do, they're all great and I find the GBA versions to be the best
DS - Okamiden, not out here, but I loved Okami, and it's the only game I'd consider getting a DS for
DSi - nothing here, still in development, and nothing interests me that much
Lynx - California Games - only game I played for the Lynx, never managed to beat it
GameGear - Bubble Bobble - yeah, I'm picking a game that's on every system in existence
NeoGeo Pocket - King of Fighers R-1 - the game selection is pretty slim, and it is in fact the only game I have for the NGP
NeoGeo Pocket Color - don't have it yet, but I'm looking forward to card fighters clash
PlayStation Portable - I kind of want to cheat and say Persona 3 Portable, not much standing out otherwise though, except for WipEout Pulse and Monster Hunter.
N-Gage - Mile High Pinball - still the best version of pinball ever, for a video game system
N-Gage 2.0 - One - best fighting game ever, not in terms of story or character design, but in terms of how the fighting system actually works
iPod touch - still current and going through a lot of games
I missed out on a few consoles that don't interest me for any games at all, aside for the multiplatform ones (TurboGrafx 16 for Bomberman 93...)
Here are mine
Computer:
DOS - Wing Commander: Privateer Gold - the game ended a bit too soon, but that was because I wanted to play it much, much more. The gameplay works well, the story is good, and some of the characters I actually ended up caring about.
Windows 98 - Deus Ex - this shouldn't come as much of a surprise, it has RPG elements, which I absolutely love, stealth elements, which I absolutely love, and great FPS gameplay, which I absolutely love. Oh yeah, it's also cyberpunk, which I love.
Windows XP - Unreal Tournament 2004 - UT99 almost made it in for Windows 98, but 2004 takes everything good about it, and either keeps it or makes it better. The single player mode with selecting a team and earning credits is also pretty sweet.
Windows 7 - I haven't decided yet, plus it's rather hard with new games coming out this year that I'm very, very interested in.
MacOS Classic 68k (System 7.5) - Escape Velocity - EV Nova is good, and servicable for Windows, but I feel the original is still the best, somehow they just got it right on the first try, plus captain hector is just a little less annoying
MacOS Classic PowerPC (System 9) - Nanosaur - it's just a plain good game, and actually creative as far as shooters go. I also know a couple people who bought an iMac just for this game. I don't think I'd ever get tired of it.
OS X - Bubble Trouble X - kinda cheating since it's a remake from Classic, but I picked EV earlier, and could have done EV Nova here.
BeOS 5 - can't remember the name of it, but that one RPG that came with the install was pretty fun
Home Console
NES - Crystalis - I really dislike Zelda, but Crystalis worked quite well, good gameplay, interesting story, actual character advancement more reminiscent of a well fleshed out RPG instead of Zelda's symplistic heart boxes.
SNES - Super Mario All Stars - kinda cheating to pick a compilation, but there isn't a single SNES game that stands out to me as one I really want to keep playing
N64 - Rogue Squadron - haven't played many N64 games, but that's the only one I really enjoyed.
GameCube - Mario Kart Double Dash - the gameplay is unique among Mario Kart games, being able to have two players on the same Kart is pretty sweet, and also helps out for party games where one person might not be a great driver but can still have fun shooting powerups.
Wii - generation isn't finished, and I'm still finding new games for it, plus Xenoblade might get ported.
Master System - Ecco The Dolphin - it originally came out on Genesis, but that's gonna be taken up, and I never actually played SMS
Genesis - Ristar - still one of my favourite games of all time, and it disappoints me that it played a back seat to Sonic. Of course Ristar may have been butchered as badly as Sonic otherwise
Saturn - I had one, didn't find a single game I liked, but I never got my hands on Sturn Bomberman, so that.
Dreamcast - still haven't got my hands on one. Eventually though.
Neo-Geo - same, although it's probably easy to go to Metal Slug or KoF with it.
PlayStation - Final Fantasy VIII - pretty much every other PlayStation game I've played has been updated and has better gameplay on a newer console. FFVIII is pretty unique, and to this date still hasn't been redone. Also one of my favourite Final Fantasy Stories.
PlayStation 2 - Persona 3 FES - managed to dethrone Final Fantasy X for me and set a new bar for immersive storytelling RPGs
PlayStation 3 - it's probably cheating to put Little Big Planet 2 in before I've even played it, but with user generated content it's something like 20 games in 1.
Xbox - Baldur's Gate Dark Alliance - my PS2 and GameCube slots were already taken up, while I like the GB story, the mechanics sucked. Dark Alliance re-did them and does Diablo better than Diablo, while doing BG better than BG.
Xbox 360 - Bayonetta - Dead Rising is fun and unique, but Bayonetta is a finely crafted beat-em up, and there'll be endless replay value trying to eventually get straight pure platinums on the hardest difficulty.
Commodore 64 - Great Giana Sisters - I'm relying on nostalgia here, but Chris Hüllsbeck made a great soundtrack too
Handhelds
GameBoy - Super Mario Land - perfect gameplay, perfect and varied level design, great music. I never get tired of playing it
GameBoy Color - Dragonball Z Legendary Super Warriors - I really wanted to put Super Mario Land 2 in here, but that would be cheating. GBC was a low point in my opinion
GameBoy Advance - Kirby and the Amazing Mirror - any Kirby game would do, they're all great and I find the GBA versions to be the best
DS - Okamiden, not out here, but I loved Okami, and it's the only game I'd consider getting a DS for
DSi - nothing here, still in development, and nothing interests me that much
Lynx - California Games - only game I played for the Lynx, never managed to beat it
GameGear - Bubble Bobble - yeah, I'm picking a game that's on every system in existence
NeoGeo Pocket - King of Fighers R-1 - the game selection is pretty slim, and it is in fact the only game I have for the NGP
NeoGeo Pocket Color - don't have it yet, but I'm looking forward to card fighters clash
PlayStation Portable - I kind of want to cheat and say Persona 3 Portable, not much standing out otherwise though, except for WipEout Pulse and Monster Hunter.
N-Gage - Mile High Pinball - still the best version of pinball ever, for a video game system
N-Gage 2.0 - One - best fighting game ever, not in terms of story or character design, but in terms of how the fighting system actually works
iPod touch - still current and going through a lot of games
I missed out on a few consoles that don't interest me for any games at all, aside for the multiplatform ones (TurboGrafx 16 for Bomberman 93...)