I'm interested in new shitcoin designs. So far these three have caught my eyes
Prime:
9th proof:
zkcoins:
If humanity moves to another planet it'll be a new chain anyway, even if using the Bitcoin implementation, so it's better to have some new designs ready :D
GitHub
GitHub - LNP-BP/layer1: Paper on new bitcoin layer 1 design
Paper on new bitcoin layer 1 design. Contribute to LNP-BP/layer1 development by creating an account on GitHub.
GitHub
GitHub - adambor/The9thProofOfFolding
Contribute to adambor/The9thProofOfFolding development by creating an account on GitHub.

Gist
zkCoins: A payment system with strong privacy and scalability, combining a client-side validation protocol with validity proofs
zkCoins: A payment system with strong privacy and scalability, combining a client-side validation protocol with validity proofs - zkCoins.md