Ubiq is an Ethereum fork that aims to create a more stable smart contract platform for building DApps. Ubiq's protocol currently uses a Proof-of-Work (PoW) consensus mechanism, but will switch to Proof-of-Stake in 2019. The network is powered by the UBQ coin.
Ubiq's goal is to create a reliable and stable platform for developing DApps by modifying Ethereum's code base with important changes that will make it more secure and reduce instability. Consensus is based on their Flux Difficulty Algorithm, which is designed to constantly adjust the hash rate to protect against network attacks.

ProximaX is developing a NEM-based platform with several on-chain and off-chain protocols. At its core, ProximaX is based on the NEM blockchain, and is designed to be an all-in-one platform for developing DApps. The platform has several parallel layers that are intended to provide decentralized storage, messaging, streaming, and content delivery services. The network is powered by the NEM-based XPX token. ProximaX intends on using a hybrid consensus mechanism for validating value transfers on these layers. Consensus will be driven with a combination of Proof-of-Importance (PoI), Proof-of-Storage (PoSt), and Proof-of-Bandwidth (PoB).

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.