Historically (not necessarily in this order):
- Mass Effect trilogy (both the story, and ME3's multiplayer/coop)
- Red Dead Redemption 2 (if only they updated the multy even just 1/3 as often as GTA... idk how they could kill a game like this 😔)
- GTA (III, then San Andreas, then V)
- Conan Exiles (still my favourite survival/exploration/base-building game)
- Star Wars: Battlefront I and II (2005, multiplayer)
- Halo (especially the PC multiplayer of the 2nd title, see the discussion under Burnley's thread)
- Star Wars: KotOR I (personally liked the second title less)
- Star Wars: TOR (obviously not as enjoyable as KotOR plot-wise but I still have a lot of hours in it along with friends, and a f*ckton of game money I'll never get to spend lol)
- Terraria (co-op, it did beat my àss when I soloed it)
- Minecraft (multiplayer only, when I used to have a server with my cousins)
- Sins of a Solar Empire (multiplayer, RTS)
- Section 8: Prejudice (multiplayer/coop; worth mentioning for the amount of hours I spent in the MP)
Currently playing:
- Valheim