I would recommend you to take a look at TrustNote as well. As a new DAG based distributed ledger, TrustNote is designed to enabling fast and scalable decentralized applications for everyone on every device at a low cost. Influenced by DAG-ledgers like Byteball and IOTA. TrustNote takes the commonly used DAG consensus model a bit further and on the top of it, a proof-of-work based consensus scheme is proposed to encourage fair and trustable witness node selection through mining (proof of work).
You can find more information about TrustNote from https://bitcointalk.org/index.php?topic=3116483.0