E.V.O. follows the story of Evolution on Earth, and yet manages to be a creation myth at the same time. The game begins with Gaia, daughter of Sol, the sun, creating life on Earth, and encouraging all the life-forms to compete to evolve. The one who eventually reaches the highest pinnacle of evolution will then become her husband and partner in the garden of Eden.
The gameplay involves wandering throughout stages, attacking other animals and then eating them to gain evolution points, which could then be spent to upgrade your avatar in various ways, depending on player preference. The game progressed through five overworld maps, the ages of fish, amphibians, dinosaurs, mammals, and of eden, each of which contained a number of smaller accessible stages, similar in execution to Super Mario World.
Of course, no RPG is complete without some complications, so developer Almanic threw in some strange spheres throughout the game, which have been granting the creatures who consumed them extraordinary evolutionary powers and transforming them into gargantuan beasties, which the player is then tasked with taking out.