I first previewed Anomaly: Warzone Earth back in January, and then saw the iOS version at GDC. It's an excellent real-time strategy game, kind of a reverse tower defense, where you need to escort a military convoy through an area full of enemy towers. I enjoyed the game when previewing it, and if it sounds like your cup of tea, the title is now out and available on Steam for both Mac and PC as well as the Mac App Store. It's usually $9.99, but there's a launch sale on for just $8.99 on Steam, so if you need a free-time filler this weekend for under ten bucks, give it a look.
The iOS version is still due out soon, and I really liked what I saw of the game on the iPad, though it's pretty different -- more of a fast-paced version than the deeper desktop client. It's supposed to be out by the end of the month, so we'll keep an eye out for that one as well.