I’ll start: Dwarf Fortress. Not found anything close.
Factorio is pretty fun
The factory must grow
Rimworld.
Kingdom (and the follow ups).
Civ games.
Stardew Valley
@IndependentRanger too many to list, but my money goes to RimWorld, No Man’s Sky (via Proton), Stardew Valley, TMNT Shredder’s Revenge, Axiom Verge, Hollow Knight, Starbound, Valheim, VVVVVV, VirtuaVerse, Celeste, Undertale, Crosscode, Crypt of the NecroDancer, Dead Cells, Jupiter Hell, and a few other games that escape me at the moment.
FTL has held up surprisingly well
Morrowind (via OpenMW) is a classic. I’ve put in quite a few hours into Terraria as well. Through Lutris/Wine, I’ve also been enjoying the classic infinity engine games (Baldur’s Gate, Icewind Dale, etc).
Cataclysm: Dark Days Ahead
I’m assuming you’re talking about native Linux games?
If so, KPatience. lol
Kerbal Space Program has been consistently my most played native Linux game, followed closely by RimWorld.
Honestly, with Proton, the answer is “many of them”, so it all depends on your personal taste!
My current highest Steam counter goes to Stellaris, the Paradox 4X space strategy title.
