Hole is pretty fun. Singleplayer extraction shooter with some light paranormal elements. Enter levels, hold off against waves of enemies from different factions that will fight each other and get stronger the longer you stay in a level, complete quests, unlock new levels and weapons/attachments/ammo types.

Guns will jam and have to be cleared manually if you overheat them. Shotguns etc. have to be loaded and pumped manually so it can get pretty frantic if you run out of ammo or jam face to face with an enemy.

Costs around 3 bongbux so 4 dollars?
Dev has said there won't be any more content updates but there's a lot there to keep you going.