Hands down, my all time favorite game is the Little Big Adventure series (“Relentless” and “Twinsen’s Odyssey” in the states) - yes, it’s two games (and always the lingering hint of a third), but I count them as one. Bonus points for those of you who see my attempt at a connection with it.
In terms of hours put into a game, I’ll list these as best as I can recall:
- Ultima 7 (part 1 & 2)
- Team Fortress 2
- Warcraft 2
- Ultima III
- Ultima IV
- The classic Infocom text adventures (I’ll just lump those together)
- Rastan
- SimCity 2000
- Thief
- Morrowind
I’d like to put Planescape: Torment on here, but I keep running into a crash part way into all the playthroughs I’ve done with it, in every imaginable configuration I can come up with on modern hardware.