Stellar is a decentralized protocol for sending and receiving money, in any pair of currencies, directly on the internet. Stellar enables users to transfer money on their network directly, without banks, and without fees. It was originally created by Jed McCaleb, the founder of Mt. Gox and co-founder of Ripple.
Stellar has its own native coin called Lumens (XLM). All users must hold a minimum of 20 Lumens in order to ensure their authenticity and to maintain a wider distribution and free flow. Users must spend 0.00001 XLM in order to transfer fiat currencies. This provides the network with more liquidity for less popular currency pairs. Lumens are an inflationary currency with a fixed increase rate of 1% per year.
The network uses the Stellar Lumens Consensus Protocol (SCP). Unlike PoW or PoS consensus mechanisms, SCP relies on a Federated Byzantine Agreement (FBA), in which specific groups of nodes are chosen to arrive at transaction agreement. This provides the Stellar network with more decentralized control.
Lightyear.io, a for-profit entity of Stellar, was launched in 2017 as the commercial arm of the company.

Fiii Coin is developing an ecosystem designed to promote the wide spread adoption of a variety of cryptocurrencies. Their payment terminal will be compatible with wide range of cryptocurrencies, and will be comprised of a wallet, exchange, and DApp development plugins. The Fiii blockchain has a Delegated Proof of Capacity (DPoC) consensus mechanism.

BitcoinDark is a fork of Bitcoin with a poorly defined purpose and use case. BitcoinDark is based on the InstantDEX protocol, a decentralized exchange for BitcoinDark and other cryptocurrencies supported by the project. The platform is also supposed to include a Pegged Asset Exchange (PAX) to allow users to buy and sell pegged assets – including fiat currencies, commodities, ETFs, and stocks.
BitcoinDark is a Proof-of-Stake (PoS) currency that has gained a significant market cap, but the project has failed to show how its vision will be implemented or how it will add value compared to other blockchain projects.