Hi there, I'm Matt Sergei (do call me Matt) and would like to help you (25 years a webmaster and IT developer).
So instead of automated bids from others I'm asking you about your in-game coordinate system, how Leaflet is used (with geolocation based maps or not) and what is your detailed requirement e.g. does a Leaflet layer serve to handle mouse clicks and other operations (probably is vice versa)?
E.g. what data do you get from a user and what do you need to have converted one-way or both ways.
Looking forward to your reply,
Matt