The player initially uses mouse or joystick to control an insect, which must avoid predators, find some food, and then find another insect of the same species and mate with it. The player can then unlock one of several "genes", altering the value of which changes their creature. Some changes are only cosmetic and leave the creature in the same species; others can, for instance, make the initial insect a new species with wings and capable of flight. After unlocking multiple genes the player can become a fast dog-like quadruped, a bird, a scorpion or a humanoid. The game does not end until the player starves, is killed by another creature, or deliberately "evolves" into a plant.