Mindustry is an excellent tower defense, Factorio-like game. It's a little tricky to play without a mouse but is very polished. Then there's Shattered Pixel Dun

Mindustry is an excellent tower defense, Factorio-like game. It's a little tricky to play without a mouse but is very polished. Then there's Shattered Pixel Dungeon, a fun turn-based roguelike RPG. Both are FOSS.