shoggouth

"NTRU encryption algorithm, is an NTRU lattice-based alternative to RSA and elliptic curve cryptography (ECC) and is based on the shortest vector problem in a lattice (which is not known to be breakable using quantum computers)."[0]

Please consider the potential for this - I think you could make something really fun and something people would be willing to pay for.

But the problem is you need a world someone else created (or one you painstakingly create yourself). You could consider Conan's Hyborian Age, H.P. Lovecraft, Sherlock Holmes, or Peter Watt's work[0] for a known world that is public domain to base your project on.

Best of luck!