We reviewed the title back in February and while the graphics and styling was top notch, the touch screen based control system left a bit to be desired:
...Bullet Asylum has a wonderful neon look that helps it feel both classically eighties and futuristic at the same time. It has three different gaming modes; the arcade mode of regular waves (with a big "boss" every five waves) and turrets replenishing and upgrading over time; survival mode where you start with every turret available and in play, and a lot of enemies ready to descend; and architect, where you purchase the towers and upgrades as you play through.
You can pick up the updated version of the app, or the free trial, via Marketplace on your handset, or via the AAWP App Directory.