Aliens! (Demo)

The Defence Captain needs your help to eradicate the waves of aliens! Before each level, a reel will spin to decide what underhand tricks the next wave will try out...

Invisible Invaders: The aliens are using some sort of cloaking device, though shooting one will briefly reveal the others!
One Shot Round: The aliens have interfered with our weapon systems - you can only fire one shot at a time.
Angry Aliens: If the aliens have had enough of your expert gaming skills, they'll send a wave of their most aggressive elite your way...