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.

Vertcoin is a cryptocurrency with a strong emphasis on keeping the ecosystem as decentralized as possible. Vertcoin was designed with the goal of being easily mined by all users and to resist the centralizing tendency of specialized mining operations. Vertcoin has a Proof-of-Work (PoW) consensus mechanism that is ASIC resistant, and uses the Lyra2RE mining algorithm.

Mindexcoin is developing a universal payment platform powered by the Ethereum based token, MIC. Their marketing materials do not clearly outline any unique selling points, or advantages, that it will provide compared to other blokchain-based payment platforms.