I said "your" rather "the" in the title thread as the answers will always be subjective anyway. Top ten games, in no particular order, for me are:

Suikoden 2(PS1)
Street fighter II Hyper fighting(Arcade,Snes, Genesis,XBLA)
Zelda 3: Link to the past(Snes,GBA, Virtual console)
Final Fantasy VII(PS1,PSN)
Terranigma(Snes)
Super Mario Bros' 3(Nes,GBA,Virtual console)
Final Fantasy XI(PS1,PSN)
Super Street Fighter IV(Xbox 360,PS3,Arcade)
Suikoden V(PS2)
Suikoden(PS1,PSN)

I'm sure I posted my top 20 in another thread but narrowing it down to ten seems like a challenge. Here we go:

1) Disgaea: Hour Of Darkness [PS2]
2) Alundra [PS1]
3) Metal Slug 3 [PS2]
4) Resident Evil 4 [GC]
5) Animal Crossing [DS]
6) We Love Katamari [PS2]
7) Final Fantasy VII [PS1]
8) Advance Wars: Dual Strike [DS]
9) Metroid Prime [GC]
10) Okami [PS2]

Narrowing down to ten was quite hard but I would be happy with these. A nice bit of variety between them all.
The ones that didn't make it:

11) LoZ: Link's Awakening [GB]
12) Super Metroid [SNES]
13) Chrono Trigger [SNES]
14) Street Fighter Alpha 3 [PS1]
15) Castlevania: Symphony of the Night [PS1]
16) Killer7 [GC]
17) Resident Evil (REmake) [GC]
18) Panzer Dragoon Saga [Saturn]
19) Ikaruga [GC]
20) Super Mario Bro's 3 [NES]

Damn, that lists looks just as good, if not better in some cases. So difficult.

I think I'll just list the games I spent the most time playing, there must be a reason for that. All pc games except for one, which can be emulated on pc now.

Diablo
Diablo II
Quake 3 Arena
Quake 2
Baldur's gate II: Shadows of Amn
Fallout 2
Street Fighter III: 3rd strike
Hexen
C&C Red Alert
World of Warcraft (Noo! : ( ... Oh well)

I have some dubious taste.

The top 4 is accurate but after that everything is in random order.

Suikoden 2
Suikoden 1
Suikoden 3
Final Fantasy VI
Zelda A Link to the Past
Super Castlevania IV
Castlevania Symphony of the Night
Castlevania 3 Dracula's Curse
Yoshi's Island
Breath of Fire 3
Breath of Fire 4
Diablo 2
Age of Empires 2
Xcom Enemy Unknown
Warcraft 2
Actraiser
Secret of Mana
Super Metroid
Phantasy Star 4

I forgot one game... Dragon Quest VIII belongs on my list as well.

Super Mario Land 2
Kirby's Dream Land 2
Super Mario Bros. 3
Super Metroid
Super Mario 64
Final Fantasy Tactics (PS1)
Final Fantasy 6
Dragon Warrior Monsters
Pokemon Blue/Gold/Diamond
XCOM UFO Defense
Half Life Series
Garry's Mod
Team Fortress 2
Left 4 Dead (Atmosphere)
Left 4 Dead 2 (Gameplay)
Cave Story
Touhou 6: Embodiment of Scarlet Devil
Touhou 7: Perfect Cherry Blossom
Touhou 8: Imperishable Night
Touhou 5: Mystic Square
Concealed the Conclusion
Dodonpachi
Donpachi
Gradius III
Axelay
Monkey Island: 1-3
Fallout 1-3
Darius Gaiden
Super Smash Bros series
Mega Man series
Mega Man X series
Mega Man Battle Network 1-3, 6
I'm sure there are a lot more

Super Mario World (GB)
Super Mario Land (GB)
Super Mario World: Yoshi's Island (SNES)
Mario Kart (SNES)
Mario Kart (N64)
Mario Kart (Wii)
Super Mario 64 (N64)
Kirby's Dream Land (GB)
Dragon Quest - Monsters (GB)
Pokemon Blue/Red/Yellow (GB)
Zelda - A Link To The Past (SNES)
Final Fantasy VII, VIII, IX (PS1)
Legend Of The Dragoon (PS1)
Spyro - Year Of The Dragon (PS1)
Shin Megami Tensei - Persona 3 + 4 (PS2)


Can't somehow think of more...

Basically a combination of most of the games everyone has already mentioned. Less work for me!

Chrono Trigger (SNES)
Chrono Cross (PS1)
Xenogears (PS1)
Final Fantasy VIII (PS1)
Shenmue (DC)
Suikoden V (PS2)
Front Mission 3 (PS1)
Lost Odyssey (Xbox 360)
Resident Evil (PS1)
The Legend of Zelda - The Ocarina of Time (N64)

Ragnarok Online (PC)
Baldur's Gate II: Shadows of Amn (PC)
Final Fantasy XII (PS2)
Ace Combat 5: The Unsung War (PS2)
Metal Gear Solid (PS1)
Resident Evil 3: Nemesis (PS1)
Front Mission 3 (PS1)
Brave Fencer Musashi (PS1)
Taiko no Tatsujin (Arcade)

I believe I speak for most of us here when I say that games nowadays do not have the same value that they used to have in older systems. They are just not that great anymore and you can't seem to get that old feeling of excitement with these new games. I can't imagine my little brother - playing Modern Warfare 2 or Metal Gear Solid 4, would get the same feeling I had when I was a kid playing the original Metal Gear Solid on the PlayStation.

I forgot to add another one,

Silent Hill 3 (PS2)

Final Fantasy VII
Xenogears
Suikoden 2
Valkyrie Profile: Silmeria
Final Fantasy IX
Disagea: Hour of Darkness
Suikoden 3
Ninja Gaiden Sigma
Spyro Series when it was still on PSX
Tales of Symphonia

I haven't played video games much & the last system I had was a Super Nintendo , so because of my limited playing experience, Donkey Kong Country was definitely my favorite. I always loved that game.

Super Mario
Super Mario 2: the 6 gold coins
Doom (all of them)
Duke Nukem
Quake
Resident Evil 4
Call of Duty: Modern Warfare 2
Mario Kart for the Wii
Metallica Guitar Hero
Guitar Hero 3 and 4

Ooops double post

Zelda Ocarina of time [N64]
Zelda majoras mask [N64]
A link to the past [Snes]
Final fantasy 7 [PS1]
Shenmue [Dc]
Shenmue 2 [Dc]
final fantasy X [ps2]
final fantasy X-2 [Ps2]
Final fantasy CC [PSP]

videogames or simply games?

in no real order

Cannon Fodder
Doom
Marathon
Decent
Everquest
Interstate 76
Rainbow Six: Rogue Spear
Morrowind
Aliens vs Predator 2
Diablo 2
Quake 2
Halflife
Team Fortress
Tekken Tag Tournament
Ocarina of Time

and still my favourite game
Redmoon

PC
Diablo I & II
Lineage II
Quake (the first one)
Command & Conquer
Starcraft

Sega Genesis//Megadrive
Sonic 3
Super Street Fighter 3
Rock & Roll Racing

PSX
Valkyrie Profile
Castlevania SOTN
Metal Gear Solid
Raystorm
Bloody Roar II

PS2
Persona 3 FES
Ar Tonelico I & II
Soul Calibur III

PS3
Bayonetta
Soul Calibur IV
Super Street Fighter IV
Metal Gear Solid 4

NES
Super Mario Bros. 3

SNES
Terranigma
Megaman X3
Final Fantasy VI

Gameboy
Zelda Link's Awakening

GB Advance
Metroid Fusion
Megaman Zero

Arcade
Marvel vs Capcom 2
Wonder Boy in Monsterland

I tried really hard to reduce de list as much as possible, i really remember having GREAT times with all of those games.
if i have to chose my GREATEST GAME OF ALL TIME i think that will be... (taking my time for thinking).... (thinking again)... Persona 3 FES... Really, the feeling you get playing this game, the very end game, is so touching, i really felt like the world was ending and... well, you get the idea =)

final fantasy 7

Every color of Pokemon, even the modded versions.
Every GTA series on all systems.
Just about every Sonic the Hedgehog adventure game.
Every version of finial fantasy, cause just choosing one isn't easy for me.
CoD4, MW2 and CoD BO, just those 3 cause the others are to outdated for me to get into.
Star Ocean series, they're epic.

I think I got around 50 or so but yeah that should sum up a vast amount of my greatest of all time.

You have some great taste. I almost expected to see Parasite Eve on there. Rock n Roll Racing was permanently attached to my Mega Drive for a long time.
Also I can't believe Labrat named Cannon Fodder. That's so cool.

Tetris.

I'm so bad at Tetris but I play it anyway for the music.

Now that's what I like to hear- I straight-forward, definitive, confident choice.