Fluidity (short for: FDT) is a public blockchain game ecosystem based on a multi-chain architecture. Digital commodities within the ecosystem can be sold as liquid assets through trustless (i.e., fully secure) smart contracts executed using blockchain technology. FDT primarily serves three major categories of the entertainment industry: gaming, esports, and film & television, each forming an independent sub-chain. Unlike traditional side-chain architectures, in the FDT multi-chain system, all chains do not need to synchronize main chain data. They share a single virtual cryptocurrency, FDT, which is used for exchanges and incentives related to maintaining the system infrastructure and technological research and development. Whether its user consumption, project parties raising funds, content creators publishing content, or advertisers placing ads, FDT is required as the sole tool for value exchange. In the FDT base main chain, the default consensus mechanism is POS+PBFT, addressing the drawbacks of DPOS, such as moving towards "centralization" and "oligarchy," thus achieving true decentralization.