I’ve been getting really into Vampire: The Masquerade - Bloodlines and Redemption, old school Runescape, Ragnarok Online, Arcanum, Diablo II, and other old classics lately, and I’m looking for more 90s/early 00s PC games that will run on my new Thinkpad E15 G4 running Arch Linux.
Caesar 3 is a fantastic city builder that will run on just about anything. https://store.steampowered.com/app/517790/Caesar_3/
I highly recommend looking into Spiderweb Software games. They’ve been pumping out top down turn based tactics rpgs for years now. I am not sure of the viability on Linux, but I’m sure there is a workaround if anything.
The Avernum series in particular is great if you’re into detailed character building, exploring, and high difficulty optional quests/bosses!
Planescape: Torment is a classic from that era
I’d add Baldurs Gate 1 & 2 to this as well, may be the best crpgs ever imo! Planescape and Baldurs Gate both use the infinity game engine if I recall correctly.
If you’re looking for something a little more modern but with a very similar feel to those, I really like Pillars of Eternity.
