Players must fling asteroids at planetoids to build up their mass and composition in order to create planets. Asteroids come in different shapes, sizes, and mineral compositions of carbon, ice, water, iron, nickel, and metal. The minerals in an asteroid determine what type of planet is created. Planetoids act as the core for planets and have initial zero composition values that increase as asteroids are flung into them. Different mineral combinations result in planet types like rocky, icy, water, or metallic worlds.