UFO Repulsion

Can be found on the Play store, but gives error code -2. I don't know why that is, so if anyone can help, that' be great.

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At one point in time, a city comprised of five houses existed peacefully. But one day, spaceships began falling from the sky above them. Realizing that their housed could not take much punishment from the falling debris, the citizens created a massive turret to protect them. However, because of the villagers' inexperience, the missiles did not destroy the UFO's. Instead, the spaceships were knocked off course and away from the city.

UFO's continue falling to this day, and citizens continue shooting dud missiles at them. How long can they last?

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Physics-based UFO deflection.

No points, no high scores, no sound, no menu screen. This all to make starting the game faster.

Further development may include a menu that allows quick starting as an option, as well as a tutorial. Everyone i've had playtest it has figured out the controls by the end of the first game and the general strategy by the second.

Any suggestions (especially regarding game balance) would be appreciated. This is my first game on here.