The session codes font could be more readable, we also had that issue for a moment when some pixelart letters were not fully readable for my friend (that doesn't play many pixelart games), also the copy button somehow does not work in the browser (it gets blocked, at least on mine and my friend's laptops, some security issue) and later pastes invalid code - maybe those are the reasons :) It also did not work in browser on any other OS than Windows for me and my friend (we tried linux+windows and linux+mac and windows+mac combinations before we tried windows+windows, not tried any of the native builds - it's impressive btw you got smooth multiplayer in browsers!)