I've been playing a number of games I used to play when I was younger.
Namely: Star Wars Rebel Assault II, Descent II (LAN multiplayer works perfectly, thank you GOG.com), and Tyrian 2000. Just got Star Wars Racer up-and-running on my Mac recently (with a joystick!) so I've been playing that too.
Tried some Don't Starve Together recently too. Works really really well for a beta.