In December, we previewed a game from Japanese developer Izumi Studio which demonstrated an alternative method for control for a shoot-'em-up that offset your finger into an otherwise unused area. Versions of this control method exist in other games games such as 2079 and Centipede but not really in what we'd call a traditional scrolling shooter.
The game which has now been released in the U.S. market and is called Internal Force [App Store] and is available for free. It does offer a fun but very challenging game comprised of multiple battles with individual "boss"-type enemies. In the meanwhile, you need to dodge a multitude of enemy fire.
The game offers three types of control: "Flick", "Gamepad", and "Accelerometer". "Flick" (the default) is the one to use and is demonstrated in this video.
The use of an "off" screen area allows you to not obscure your ship while you try to dodge enemy fire. The game works pretty well and the flick control allows some precise movements. The gameplay area, however, is noticeably small. As a free game, however, it's certainly worth a try.
App Store Link: Internal Force, Free