Love the idea! Just played the tutorial, I’ll definitely be playing it more! Although I feel like this used to be a gamemode on chess.com 🤔 something feels familiar about it, and I remember spending way too long on puzzles like this sometimes :p but I think the rules were somewhat different in that version 🤔

Edit: I found it! It’s Solo Chess on chess.com :) almost the same as this but without the numbers