Sanctum 2 is a bit older, but it holds up as a solid FPS tower defense hybrid. It's often on sale for around $4. The dlc is also well worth it, doubling the base game content.
Battle Bit Remastered
Children of Morta
Risk of Rain 2
Crab Champions
Echo
Gunfire Reborn
Journey
Hypercharge Unboxed
Journey to the savage planet
Perish
Scanner Sombre
Severed Steel
Shatterline
Strange Brigade
Zedfest