**Rule:** Strictly simple character substitution (+ maths if needed)

**Base (note):** My Base-63 = regex [A-Za-z0-9\s] = 26+26+10+1 = 63

**Method:** I suggest simple Caesarian Substitution

**Prohibited:** NO JavaScript allowed

**Prize:** A large sandwich. Or Amazon gift of $20

**Submission:** (i) Here, with code to try on a TW. (ii) With an example.

**Proofs**: (i) What is 1000 (decimal) in (my) Base-63? (ii) What is 1000 (Base-63) in decimal? (easy-peasy)

Ever hopeful

TT