BESIDES GMOD
Mine has to be a few:
RED DEAD REDEMPTION 2: Honestly one of the best games I've ever played, with an awesome soundtrack and AMAZING story! Very fun!
L.A. Noire: A late 40's detective game, feeling like a Noire film. Really fun, LONG but GOOD story but not much content once you finish, besides a free roam.
Fallout New Vegas: Honestly, it's also one of my favorites. Honestly, just get it. j o h n n y g u i t a r
SWBF2 2005: Childhood. Still holds up.
Hearts of Iron 4: One of the easier Paradox titles, but still pretty fun when you get the hang of it. I might be biased since I'm a history nerd, but it's still fun.
Battlefield 1: It's fun and I really like the uniqueness it brings with the WW1 setting. Still has a good amount of players.
Leave your favorites below! (also if you want to play one of these games with me or you want me to teach you, just ask! xd)