Added text stroke for better readability.
Diffuculty now increases as time passes.
Added Greek and German translations (thanks to Fivos Asimakop).
The game now uses accelerometer, not orientation sensor (suggested by Fivos Asimakop), removed wake lock.
Few other optimisations.
Touch the screen, rotate your device to gain health, kill enemies and protect the core as long as possible!
This game is free and open-source. Everyone can use it's sources. Feel free to fork me on github: http://bit.ly/coregame.