They Came From the Ground is a two-player volleyball game which can be played against an AI opponent or a friend. Each player controls a circular blob-shaped character and must try to bounce the ball (or balls) onto the floor of their opponent's side of the court. Players can also jump onto their opponent's side and push them around, but this is inadvisable as doing so leaves their own side undefended. Players also have the ability to grow or shrink in size. The AI opponents have characteristics which differ depending on their color; for example, Green only plays with one ball on the court, while Purple rarely jumps but only plays with two balls. The first player to reach 5 points wins the match.