The outer planet has been invaded by aliens! You need to save the planet and fight back. The game is free to play online. Outer planet alien online game is a free browser game where you fight aliens on different planets. alien invasion,save the planet,free online game,arcade game,hypercasual game,planet game,world game,adventure game,alien game,online game,browser game,fight aliens,outer planet,space game,arcade,hypercasual