The Sapling Pre-Installed Game
Design plants and animals. Fast-forward time to and watch the ecosystem work like a charm or slowly fall apart. A sandbox mode where you can skip time and turn on random mutation, allowing true evolution. An instinct system where you can specify what an animal should do when it hears or sees something. A procedural animation system so any animal can perform any animation. Procedural music mixed on the fly. Everything is set up to be easily extended by players.