most replayed game?

Shogun, Rome and Medieval Total War. I'm not talking about the sequels. Plenty of hours <3

Madre de dios es el pollo diablo!!!!!

The Curse Of Monkey Island off course =)

Breath of Fire 3 on PS1
Zelda - Ocarina of Time Master Quest on GameCube
Assassin's Creed II on PC
Skyrim on PC
Yu-Gi-Oh Forbidden Memories on PS1
Pokemon Red on Gameboy Advanced
etc.... ^^

Call of Duty and Half-Life series.

Super mario bros. on NES.. and Tetris, of course (there are many versions/clones.. I liked Tetris DS the most)

I play Romance of the Three Kingdoms series. Never get bored.

Grand Theft Auto San Andreas and im Currently in This Game

minesweeper

Any pc/console game can be replayed last i checked. Never heard of 1 time playthrough in a game before.

Peggle.

Devil May Cry 3 and 4

Pokemon (I prefer Gen 1, 2, 3)
Half-Life (all of them)
GTA (SA)
Super Smash Bros. Melee (as well as the N64 original)
Ratchet & Clank (1, 2, 3, Gladiator/Deadlocked)
Gran Turismo
Portal
Resident Evil
God of War
Diablo
Unreal Tournament
Super Mario World

Dark Souls. I don't know how many times but I've 385 hours played and my average playthrough is at about 16-20 hours, if I do everything.

Mass Effect "duology" :D
...feel free to play the third one as well, but I have replayed mostly the 1 & 2

For me Fable: The lost chapters was the most replayed game ever. I replayed it like.. umm.. 10 times maybe?
It's a nice game!

XCOM: Enemy Within and Civ V.

Ratchet deadlocked

If we're not listing multiplayer games (as others have done), my list is quite a bit shorter.

Diabo II - Lord of Destruction (about 6000 hours into this one)
Neverwinter Nights Collection (only 4000 hours into this one)
Warcraft III - Frozen Throne (have stopped playing this, but sunk about 2000 hours into it)
Unreal Tournament 2004 (talking about the SP campaign, here)
Black Isle RPG's (revisted every year or so)

Those are the ones I to which keep returning. I have so many games, however, that I haven't even played half of what I own. I have always tried to buy games that can be replayed, so almost everything I have can be revisited. You may have noticed that NWN and WC3 have an infinite number of mods to them.

Now, if only I had the time to game.... P

Impossible Mission (Commodore 64)
Tetris (GameBoy)
Tetris (coin op)
Bubble Bobble (various format)
Puzzle Bobble (various format)
Super Mario Bros (Nes)
Super Mario World (Super NES)
MS Pacman (coin op)
Mexico '86 (coin op)
Resident Evil (Various format)
Sonic (Megadrive/Genesis)

Depends on what exactly you mean by replayed. Saying you keep replaying CivV seems kindof dodgy seeing as your 2nd match was technically a replay.

If you mean actually going back and replaying a game you had finished and put away on the other hand then I'd have to say Planescape:Torment. Although I have, definitely stopped going back to it now the amount of times I got disappointed by a new RPG and went back and found something completely in PST is just something that really makes you love a game.

Dragon Age Origins.

This war of mine

Lego Star Wars 2

Gothic)