So first off if you cant afford games, just pirate em. Dbzer0 Lemmy instance has lots of good info for doing this. Though you'll have to learn how to set up wine n stuff via lutris to install windows games on linux. If youre concerned about legal implications around piracy, I'll get hate for this, but just limit seeding speeds to 0. Seeding is the illegal part for torrents as its the sharing of the files to others

Most of the oldschool crpgs like baulders gate 1 & 2, Icewind dale and plane scape torment should run more then fine

Factorio and rimworld should play well enough until you get into late game bases

All of the older valve titles are a good time half-life 1 & 2, portal 1 & 2 and they arnt overly demanding on hardware

For a sorta free game, old school runescape is a fun time waster and its possible to get membership via in game gold farming in f2p

Dusk and Amid evil are two very fun boomershooters that should run well enough I would think

Terraria is very fun and isn't very demanding on hardware

Could also download an nes/SNES/n64 emulator and pirate Roms for all the og Nintendo games but I'd only recommend those if you have a controller of some kind

Dwarf fortress is free but the free version is a little bit of a nightmare to understand visually, the forums have info on how to download tilesets and stuff to make it more user friendly. Though this is another game that will suffer from late game slowdown

I can't think of any other games I'd recommend atm but hoist the sails high my friend. Its how I got 99% of my games growing up