Tower defense games are great. Tired and done to death, sure, but the good ones are really fantastic. Anomaly Warzone Earth and the sequel Anomaly Korea are two of the better entries in the genre, having the distinguishing factor of playing role reversal. In these, you're not building towers, you're trying to slip past them. Now, both titles are half off on the Play Store, each costing a mere $2.
Normally, each game individually is priced at $4 and now you can get both for the same price. Not a bad deal! Back when Ryan reviewed Anomaly Korea, he loved it. Graphics, gameplay, and concept. Start to finish, it's been a favorite around the Android Police offices. Which don't really exist, but that's beside the point. This deal will be going on all week. You might want to get on WiFi before you download, though. Each title is a few hundred MB.