Hello, thank you so much for your interest in the project :) I haven't delved into multiplayer yet as there as still some things I wanna do first that I believe are more important and more useful for the users. You can read about what I have in story in the devlogs attached to this page :)
As for multiplayer, I think probably it will be the last thing I do, if it's within the realm of possibility. I'm planning to have all the features I have planned for MonMae finished sometime next year, so once that happens, I will do my research and see if multiplayer can be added somehow, because that's a feature that not only lots of people have asked for but it's also something I really want to do and implement and see in my own projects too^^