Controls:

 WASD to move, SPACE to shoot, 1,2,3,4 to repair

Why?

I tried to combine space invaders and FTL. 

Your tank can get damaged and you can repair it. You can repair the tank by hitting numbers 1,2,3 and 4 when a section of your tank is damaged. When all sections are destroyed the game ends. If you manage destroy all of the monsters then you basically win.

Enjoy!