1,110 hours on Garry's Mod
505 hours on GTA 5 Online
292 hours on STALKER: Call of Pripyat
248 hours on Skyrim
247 hours on Fallout 4
117 hours on Fallout: New Vegas
90 hours on Warhammer 40K: Space Marine
^these are all games I'd consider well-suited for your question, for obvious reasons. I'd probably have closer to 200 hours on Space Marine if I hadn't lost my all my multiplayer progress when my HDD failed.