Void Stranger, Chip’s Challenge, BABA IS YOU, and Blackshift are all Sokoban style puzzle games with minimal performance requirements and no need for a mouse.

Siralim Ultimate is a creature collector RPG that will run on a potato and provide endless grinding, if you’re into that.

The Final Fantasy Pixel Remasters of the first six games are all excellent if you’re into JRPGs.

Dungeons of Dredmor if you like rogue-likes, or you could go old-school and pick up NETHACK or ADOM.