Autonomous Worlds are fully onchain games that run on the blockchain, where the logic and state of the games are stored in smart contracts and all game data is on the blockchain. These games are open systems, constantly online, and can run independently of their creators. They invite users to build upon them and create their own extensions, leading to constantly evolving ecosystems. Autonomous Worlds can also have their own currencies, markets, and economic rules, creating new forms of economic organization within the metaverse. The development of onchain game engines is an important aspect of the growth of the Autonomous Worlds genre.