It's easy to make a side-scrolling game. It's a little harder to make a good one, and harder still to make a side-scroller that will keep you coming back. Attack From Outer Space falls into the latter category.
It's a simple game with simple controls -- you've got a slider for moving Sergeant America (yes, that's his name) back and forth, and a joystick for aiming your arsenal toward the aliens. You've got to take out as many as you can (and you get combo bonuses for being quick about it) while dodging their bombs. You'll pick up new weapons along the way, and acquire nukes for those times when only a nuke will do.
Each level has three stages, with a "World boss" at the end of each. Make your way across the U.S. in the "Adventure" mode, and you'll unlock Area 51.
All in all, it's a lot of fun, and a hell of a lot of gameplay for just 99 cents. We've got some hands-on video, screenshots and download links after the break. Check it out!