This – storing the document in the URL hash – is the kind of creative thinking that I love.
If you’ve not seen it, here’s my 2-player “word game” clone that works the same way: https://words.pico.games/
https://bsky.app/profile/did:plc:53ykobfiwdm2ihatqmwdz24l/post/3mxubutwut22h