V Systems is a blockchain platform that was developed by Sunny King, the creator of Peercoin and Primecoin. Peercoin was one of the first Proof of Stake Coins, and V Systems is designed to improve upon the consensus mechanism with a better staking system.

MetaHash is developing a blockchain platform for creating DApps. Their network has a multi Proof-of-Stake (PoS) consensus mechanism that is designed to increase transaction speeds and block formation times by using all of the nodes on the network.

Ignis is a blockchain platform that is being developed by Jeluirda; the company behind Ardor and Nxt. Ignis is a child chain of the Nxt blockchain. Jelurida is developing blockchain platforms that will enable users to develop decentralized applications, and will be based on a parent and child chain architecture.
Ignis allows users to create child chains with specific features and to create tokens that meet their needs. This project is closely related to Ardor and Nxt.