Whoa they're up to 5 now?
Ninja Kiwi has some great stuff including Zombie Trailer Park - Splatter Zombies and Save the World, but my favorite is Bloons Tower Defense 5. I've been hooked since the first Bloons Tower Defense and they just keep getting better.
Don't get me started on Tower Defense games. Bloons 3, 4 were great. People always ask why it's 2012 and we don't have technology like time travel. I tell them to go play Bloons, because I've done a LOT of time travel with that game. Now if only I could figure out how to make it go BACK in time...
Video games don't affect you negatively; withdrawal does.