For this site anyhow
Bloons TD 6 on Steam for $1.99 right now. Little tower defense type game with balloons (hence the name) for any that have not heard of it.
Ya, ya, I know...sounds crazy, but it really is a good little time waster that I mess around with every couple days or so for a bit. And it even has multiplayer (kinda) which not all that this site promotes even have
Normal price is $9.99 and I think it is worth 2 bucks easily. So for any that might be stuck with nothing to do and need a little game to waste some time with, go take a look on steam.