@gamingonlinux Half-Life 2 Deathmatch and Toontown Rewritten, mostly. Some OpenTTD and Half-Life: MMod in there as well.
HL2DM: good, kind of easy with the new summer sale players
TTR: enjoyable but kinda limited in what you can really do with it
OpenTTD: most fun with mods but I've got a rhythm that works with it and it is definitely a nice time building up railways from nothing
HLMM: I'm mixed on this one. There are plenty of neat changes, but it seems like for every two good changes there's a bizarre one or one that makes the experience worse, like as an example making the suppressor on the MP5 removable; either stick to HL1's integral or go for End of Days' SD-like flash hider for realism
I'll get to Scribblenauts soon.