Thanks for your feedback!
2- Yep, as explained in other comments here and on the community - the game was made for the other jam and a fellow designer pointed me to this jam less than an hour before deadline, and the jam organizer was fine with me submitting. Once the judging is done, I will update the files with mentions of Mapemounde.
3 - I have couple people mention this. I imagined the game as a chain between 5-6 people, but it seems there is more interest in sending it back between few people instead. I am now looking at different was of generating the string of numbers, so it is compatible with those players.
4 - I was torn between giving players creative/narrative freedom and having strict rules. My current idea to remedy this is to include it in the key. My plan is to create multiple keys (as well as provide an empty/form fillable key) to create the premise for each map. The key that exists now has a low fantasy setting implied. What would you like to see in the initial context?