So many, depends on the booted OS and what I feel like or what the kids feel like playing.

Currently doing a mix of Quake 2 single player (100%ed it on nightmare but I keep coming back to it), Half-Life deathmatch (hilarious with the kids as we try to lay out traps for eachother), Reflex Arena, Planetside 2, Age of Empires 2, OpenRA, Ion Fury, Fallout 3 and Red Dead Redemption 2. Last 3 are story modes, so they take long. Only Ion Fury is linear though, so it’s easier to come back to.