Games you keep going back to?

For year and a half - Minecraft. You can never run out of things to do in that game - in multiplayer, you're basicaly living a second life.

Baldurs Gate 2 + ToB, Fallout 2, Arcanum.

LotRO is always my fallback game but that's partly because I'm in a good kinship with regular raids, other than that I'd have to say CS.

I find myself incessantly drawn to Dead Rising 2. Something about taping together a couple of chainsaws and tearing through masses of the walking dead just does it for me.

Also Dark Sun: Shattered Lands, from 1993. Can't get enough. :)

34th playthrough?! And I thought I played it alot! XD

Only naming singleplayer campaigns that most people might not consider having replay value: I'd say Half-life series, Metro 2033, Portal 1 (I may have played it 10 times on both the xbox and pc)

I go back to Deus Ex. The original. Also, Mega Man 2.

Is dota 2 counted? >.<

Oh yeah, I remember.

Rockman X series

Grim Fandango (the most epic, most underrated adventure ever), Gabriel Knight 1&3, Fallout 2, C&C Generals (multiplayer).

Minecraft and Nuclear Dawn (200+ hours, still freaking awesome!)

GTA and

ARMA series

no one mentioned WoW? or maybe its only steam games

Max Payne 1

1) It has aged really well, still looks acceptable today imho

2) It's challenging, no health regeneration and that crap, even regular mobster kill you with a few hits

3) I just love the art-style and the humour. My Lord! My Lady! :P

For MP it's Urban Terror: super fast old school shooter, been playing that game since Dez 2007, competitively since Mid 2008

Warcraft 3 TFT - all the Fun Maps like DotA or the RPG's

Stalker: Shadow of Chernobyl
Best game ever, highly replayable with mods.
edit: Also Railroad Tycoon 2 and 3. That game never gets old.

Jagged Alliance 2
Total Annihilation
Grim Fandango (oh good, I didn't have to mention it first this time! :))
The Neverhood
Deus Ex
Beyond Good & Evil
Roller Coaster Tycoon (I think I need to reinstall the original... 3rd one's really close, but missing... something.)
Defense Grid
Super Meat Boy (/shakes fist)
and Team Fortress 2 (duh)

Mass Effect 1 and 2, Baldurs Gate cuz of Big World Mod, KOTOR series, though 1 was much better and Alien Swarm from time to time :D

Well, I used to play a lot these games:

• Tony Hawk's Pro Skater 4 (I used to play it for relaxing, now i play indie games instead of that, but damn, it were great times.)
• MAFIA (When it was released, it was like discovering porn. Great story, czech dubbing, mafia atmosphere, open world.)
• GTA Vice City & GTA San Andreas (I started with the GTA VC kinda late, after ca 1,5 - 2 years its release. But anyway, the scenery was incredible, i loved it. After finishing the story and tons of hours of non-sense playing, I started messing with new cars and textures. Then i started making them myself... So that's probably the reason why I spent thousands hours in these games, and much, much, much more on making mods for GTA series. Who was enjoying GTA with mods too? If you have so, you have probably heard about me :3, I used to use different nickname of course )

Games I keep going back now:

• Test Drive Unlimited 2 (I know, it's not perfect, but i love cars. I spend a lot of time in casino [poker] or just driving around with friends. I play it as an arcade, so on keyboard. Btw, I have 372.9 hours on record so far :D)
• Racing games: Race 07 series & DIRT3 (I need to play some racing games, right now it's RACE 07 series, and sometimes DIRT3 too. Just for hard fun with stearing wheel. But I'm kinda new guy in these games, only over 60 hours in these games so far.)
• Indie games: Audiosurf, Eufloria

Games I intend to play again:

• Half Life
• Mass Effect
• MAFIA II

Castlevania Symphony of The Night, even though I've completed it alot of times.

Borderlands is great for me

There is barely enough time now for new games let alone going back to old favourites. They may not be popular answers here but I remember how I replayed Resident Evil 3 and Parasite Eve II time and time again...

Games I played the most:
Brood War, World of Warcraft, Diablo 2 <3 Blizzard

Some games I played at least once a year since they launched:
Master of Orion 2, Heroes of Might and Magic 3, Civilization 2

Games I played the most on Steam:
Dungeon Defenders, King Arthur, Batman Arkham City

I always end up playing Mass Effect 1 and 2. Always.

Any halo titles on xbox 360.
Final Fantasy X on ps2 (f*cking love this game!).
Final Fantasy 6 and 7 (emulator, good games too).
Half life (mostly mods).
Dark Messiah of Might and Magic (beated the game 5 or 6 times already...).
Fallout 3 (did 4 playthroughs).
Super meatboy (plain awesome, never gets old).

There's probably more, but these are mostly the ones i keep playing over and over...

The whole Half-Life series, I just love them.