Offerings to Cthulhu OFF

Offerings to Cthulhu (OFF) is an open-source Proof-of-Work cryptocurrency originally launched in September 2013. Built around the Quark Hash9 mining algorithm, the network targets approximately 60-second blocks and maintains its own independent blockchain.

The original chain suffered a majority-hashrate attack in 2018 that produced deep reorganizations and approximately 533,983 counterfeit OFF. Development subsequently stopped and the network became inactive. In 2026, community maintainers recovered historical chain state and revived the project through the Restoration Hardfork while preserving the original blockchain history.

The restored network introduced additional security rules, including a maximum reorganisation depth, rolling checkpoints and signed broadcast checkpoints. Mining became permissionless again after the temporary signed-mining protection period used during the restoration.

OFF currently has a base block subsidy of 1.5 OFF per block with no scheduled end to the base emission. Seven-eighths of each standard block reward goes to the miner and one-eighth is directed to a published multisignature treasury used for reclamation, contributor grants and other community purposes.

The project also incorporates an unusual on-chain cultural component. Beginning at block 1,000,001, miners recorded fragments of public-domain H. P. Lovecraft works in coinbase data, creating what the project calls the Chain Codex. Offerings to Cthulhu remains a small experimental network, and its own documentation openly discusses its historical attack, security assumptions and remaining points of trust.