Cosmic Defenders (itch)

Cosmic Defenders is a pixelated sidescroller, fast-paced tower-defense shooter (Gosh, that description is long...)

The game is about 4 astronauts (Or one... However many you friends you feel like playing with!)that set out in the galaxy to defend different planets from other alien races. Basically most planets reward you with zaphcoins which you can use to purchase passive abilities. They also reward you with special attacks, that you can use to make beating the different difficulties a lot easier.