List of GnuPG/OpenPGP replacement (not OpenPGP compatible)

https://github.com/wbl/cpgb CPGB is the Curve Privacy Guard B, a secure replacement for GPG using ECC. (Status: Dead? last-update:2011)
https://github.com/carlos8f/salty Alternative public key encryption using NaCl. (Status: Dead? last-update: 2016)
https://github.com/TotalTechGeek/DiscreteCrypt This tool is an alternative to software like PGP, with a focus on Discrete Log Cryptography. The algorithm is currently in v2.2.5. (Status: Active)
https://saltpack.org/ a modern crypto messaging format (Status: Active)
https://github.com/stealth/opmsg opmsg is a replacement for gpg which can encrypt/sign/verify your mails or create/verify detached signatures of local files. (Status: Active)

List of GnuPG replacement (OpenPGP compatible)