The phone-desktop link is done with webrtc (it's also often used for peer2peer chat and stuff). It's medium complicated but there is a ton of boilerplate code for it out there (and most AI models will write decent code for the setup - which is how I did it here, but I've done it elsewhere without the model, which I think helps a lot for learning it).  TBH I want to set up something similar for another game in the future where your phone becomes like an old NES controller or a slingshot launcher. 

Thanks for playing it!