Stupid Invaders follows the story of five aliens - Candy, Etno, Gorgious, Stereo and Bud - who crashland on Earth and hide out in an abandoned house. However, their hideout is discovered by Dr Sakarin, an evil scientist, and his henchman Bolok arrives to capture them. The player must help the aliens escape, alternating between each of the five characters.
The gameplay of Stupid Invaders is based on point-and-click interactions with the environment. The player can carry up to six items simultaneously and use them to solve puzzles. Unfortunately, many actions result in instant death for the protagonist, often depicted graphically for humorous effect.