The source code is released under the MIT license and the game assets are released under the Creative Commons Share Alike License.
Other SkyRiot links:
App store page: http://play.google.com/store/apps/details?id=net.freedomforge.skyriot
Developer homepage: http://www.freedomforge.net
Facebook page: http://www.facebook.com/pages/Sky-Riot-for-Android/316406505130136
SkyRiot is a 2D flying shooting platform action game for Android devices. Fly a hoverboard and use an assortment of weaponry as you, an anarchist, single-handedly wage war against a totalitarian regime. Full 360-degree aiming along with total freedom of movement will keep you glued to your device for many hours as you blast your way across over 10 game maps.
The fascist regime will squash your airborne rebellion with laser equipped police officers, bazooka toting soldiers, law enforcing surveillance orbs, jet fighter airplanes, grenade throwing prison guards, even a jetpack powered security force.
Skyriotfree is the best! Thanks.