Stop the Germs! is a fast paced strategy game in which two players take turns placing, flipping, and moving hex tiles adjacent to one another and playing special effect tiles. Each player begins the game with an identical set of ten germ tiles in addition to three special effect tiles that are randomly drawn. The germ tiles contain point values between one and six as well as two tiles that can copy the value of another germ tile in play. The special tiles have varying effects on gameplay that benefit the controlling player or work against their opponent. Gameplay ends immediately when a player places their last germ tile. The player with the largest number of points worth of germs at the end of the game wins. Stop the Germs! does not require a playing board and is limited only by the flat surface that it is played on.