I know, that would be a great addition. But unfortunately I cannot do that right now.
Making online games is different to making regular games. If I'd wanted to add multiplayer, I'd have to rewrite the entire code of this game, as if I started making it from the scratch.
No, by starting from scratch, I meant starting from the very beginning (I should have written "from scratch" not "from the scratch", sorry). The game has been made, and is still being worked on, in Unity engine.
You have to wait, he's not going to put multiplayer system in this game now, if he wanted to put multiplayer on this game, then he had to start the script from ZERO!