Either SimCity 4 or Civilization IV for me

I hate these threads. Don't make me choose!

I nominate Dwarf Fortress, for its sheer depth and vision (and continuous development), if for nothing else.

Very tough since I have a very short memory.  Total Annihilation came out in the 90s.  Baldur's Gate II? When did that come out?

Borderlands by a nose in front of GC2.

Dwarf Fortress is well on its way to being the best game, but I don't think it can truly hold that title yet. It's too far from complete in my opinion; as an RPG I'd say it's still inferior to Daggerfall in a lot of ways, and Dwarf Mode is barely even a game so much as a construction tool crossed with an ant farm. Also the game as a whole lacks elegance of interface and prettiness of graphics, and tends to be tough to get into.

If the Paradox core suite was considered a single game that would qualify, but as it is I'll call them the best developer. Best game altogether is harder because it's too subjective. I'd say best RPG is either Morrowind, Daggerfall, or the latest Deus Ex, depending on preference. Best strategy is Europa Universalis III, I guess, it's the most popular of those games although I personally prefer Crusader Kings. Shooters as a genre are not suited to having a single "best" since in single player they're about a single cinematic experience and in multiplayer are about chilling with your buddies.

Really though, everything comes down to taste.

I'd vote for Total Annihilation if it was in the past 10 years. I'll go with Morrowind instead. If you didn't play it when it was new, then you'll never understand. 8) If anyone (including me) ever found out how many hours I've accumulated (and am still accumulating) in that game it would be shocking.

Deus Ex. Or was that before 2001?

ok

NOLF 1 AND 2

Sins

Half Life 1,2

Battlezone PC

Wing Commander Heart Of the Tiger

Skyrim

Deus Ex 1

Command and Conquer 1

Medieval Total War (the original). 

It was before 2001 bro   I think it came out in '99 but dont quote me on that...

Definitely one of my all time favs. 

cant choose one single game, i liked and played a lot: 

Max Payne, PES 6, NHL 2004, Call of Duty games, Call od Cthulhu: Dark Corners of Earth, W40k: Dawn of War, Generals: Zero Hour, Homeworld 2 and SoaSE.

Best game by the most amount of time sucked into it:

Sword of the Stars: Wow, there's ten million years of replayability in that one.

Titan Quest (plus Immortal Throne): I never thought I'd play a hack 'n slash this much, but they sure got everything right. Shame that THQ had to quit supporting it. I'll probably still be playing it when D3 comes out.

Medieval 2 (for the mods, although M1 and Rome had some pretty awesome ones too). That Third Age mod is the schizz.

Return to Castle Wolfenstein (released late november 2001, so only by 10 years, 5 weeks, including it!). Best FPS in a long time. You can keep your Call of Duties and Battlefields, just give me this for me and my friends for the rest of my life.

Best game by "Holy crap, where was this game all my life?"

Trine. Damn if I haven't seen a good platformer with great puzzles and mechanics in the last 10 years.

Mount and Blade (plus Warbands, I only started playing the first one a couple weeks before warbands came out). Wow, the initial gameplay felt so fresh, unique and awesome.

Portal. 'Nuff said, puzzles are awesome.