Your favourite game ever on any platform? ..

[zipper]

ET on Atari 2600...
Probably longest time spent on NemacIV and Shogo. And Flatouts on PC.

[nicholas]

Mario Kart Double Dash on the Gamecube.

[fishy_fiz]

How about on "each" platform?

Commodore Amiga - "James Pond 2: Robocod"
Commodore 64 - "Ghostbusters"
PC - "Carmageddon" (with "Stunts: 4D Sports Racing" a close second)
Mac - "Photoshop"

Atari 2600 - "Yar's Revenge"
Atari Jaguar - "Tempest 2000"
Sega Genesis - "Toejam & Earl"
Sega Saturn - "Baku Baku Animal"
Sega Dreamcast - "Chu Chu Rocket"
Playstation 1 - "Wipeout XL" or "Micro Maniacs" (tie)
Playstation 2 - "Katamari Damacy"
Playstation 3, XBox, XBox 360 - buy me one and I'll tell you.
Nintendo Entertainment System - "Duck Hunt"
Nintendo Wii - "Epic Mickey" (soon.)

Atari Lynx - "Chips Challenge"
Nintendo Gameboy/GBC - "Tetris"
Nintendo GBA - "Tron 2.0" (for the minigames)
Nintendo DS - "Space Invaders Extreme"
Sony PSP - "Echochrome"

but overall? I'd say #1:Tempest 2000, #2:Katamari Damacy, #3:Carmageddon

hehe,... stunts 4d racing, damn that brings back some memories    I had a pc owning friend who used to rub that game on his high end 286/low end 386 (cant recall which, bu it was an ok-ish but not great pc for the time). It was only a few years ago that I discovered there's also an amiga version. I'll have to check it out one day to see how it runs on something faster than an a500

[lsmart]

Invaders - any platform
Shufflepuck Café (Domark) - Amiga

[desiv]

For me, it would be Ultima IV on the Commodore 64...
One, it was just an incredible game..
Two, timing.  It was THE game when I was most into games..

Although I've played and enjoyed games since then, that was the peak of my gaming interests..

desiv

[pyrre]

Nebulus is one funny game...

On the other hand i have always returned to Diablo.

But deciding on just one favorite game is quite hard.

[lionstorm]

Kick Off 2 - final whistle and then SWOS (both on Amiga).

all the rest are just games to waste time on (and have some fun/joy too) !

[Speelgoedmannetje]

Thief (PC)
OK it didn't have the best gfx at the time, but men, there was so much in it, so much gameplay, and so much atmosphere.

[Lando]

I think Counter Strike: Source is probably the one that I have played most over the last decade, but it makes me so mad sometimes.  I think, probably, the original Metal Gear Solid on PlayStation would have to be my favourite ever.

[T3000]

Along with the original Tribes.

[yssing]

Colonization, DuneII and quake...

[XDelusion]

Oh geez, how could I exclude the Half-Life series or any of the System/Bio Shock games?!!?

Then of course there are the two Knights of the Old Republic Star Wars RPG's.

Too many games to list I say!

[kedawa]

My favorite game of all time has to be Terranigma on the SNES, it is in my humble opinion the best R.P.G. game ever on any platform...

It's definitely the best ARPG, and it's a much better game than the SNES Zelda.

[DamageX]

non-action games:
Phantasy Star IV (Genesis)
Super Robot Taisen F Kanketsuhen (Saturn)
Langrisser V (Saturn)
action games:
Megaman X2 (SNES)
Super Street Fighter II (various)
Space Megaforce (SNES)

both sides of the coin: Mount & Blade

[B00tDisk]

I'd have to say the Half-Life 2 family.

[Marcb]

Tough to narrow it down to one so here's a list
 
Elite (AMIGA/C64)
Magic Pockets (AMIGA)
Xenon2 (AMIGA)
Ultima Online (PC)
Wing Commander (AMIGA)
Privateer (PC)
Sonic (MEGADRIVE)
 
If I had to choose 1 to take with me to a deserted island then it would be Elite.