The download button opens the iTunes App Store, where you
may continue the download process. You must have iTunes installed with an
active iTunes account in order to download and install the software. This
download may not be available in some countries.
From Axes Art Amuse:
Compass mode- turret turns to north always. - turns to north, an artillery shell will fire. - Tap the compass button, to become a free mode.Free mode- A turret can be rotated by a drag. - tap of the turret, an artillery shell will fire.