An alien called Cosmi got stuck on earth after his spaceship crashed on a satellite. The only way he can return home is by gaining enough money to repair his spaceship. Unfortunately for the humans, the only way Cosmi can obtain money is by causing panic amongst them.
The player takes the role of Cosmi and can use several different weapons and gadgets to scare away the humans. You can launch a giant bowling ball, a cannon or a karaoke set to terrify the people with your awful singing. To obtain new weapons you have to scan the DNA of humans walking the streets, each having their own set of abilities. When you scare humans enough, they drop coins. Getting enough coins completes a level and ultimately, the game.
Under the Skin brings you to different locations, including Raccoon City, the place where the Resident Evil games take place. In that level you battle the ultimate foe Nemesis, who this time is entirely cel-shaded, just like the rest of the game.