Based on the original tabletop game Grro, this webgame, powered by a 100% renewable energy hosting service, simulates temperate zone succession ecology from barrren land. The game itself is easy to learn but is rooted in the science and basis of ecological succession: a well known observed principle of the cumulative establishment and formation plant types transition from grassland to old growth forests . If you like the game you can buy the tabletop version to play with other players.