PAC coin, short for People’s Alternative Choice, is a cryptocurrency with a hybrid Proof-of-Work (PoW) and Proof-of-Stake (PoS) consensus mechanism. PAC Coin aims to encourage cryptocurrency adoption by improving usability and community governance. The network will rely on a system of masternodes to help verify transactions.

Unobtanium is a Proof-of-Work (PoW) cryptocurrency that uses the SHA-256 hashing algorithm. It was designed to serve as a commodity and store of wealth that would be less vulnerable to price fluctuations. The coin's supply is limited to counter inflation, and UNO coins were distributed in a manner that would discourage centralization. UNO can be merge-mined with Bitcoin.

Primecoin is a cryptocurrency based on finding prime numbers. Identifying prime numbers plays a central role in cryptography. Primecoin's unique Proof-of-Work (PoW) consensus mechanism is able to increase transaction speeds and improve energy efficiency.
The network searches for special prime number chains known as Cunningham chains and bi-twin chains, which are of interest in mathematical research.