Apparently I am a bit tired, I AM actually in Chrome *facepalm*. The game gets stuck, when I use the mining tool and accidentally "paint" outside of the window the game is in. Which happens when you try to mark a huge area really fast haha. I don't know if this is even something you could fix, from a technical side?
Thank you so much for figuring that out :). I was able to reproduce the issue and it's definitely a problem in my code.
I filed the issue here: https://github.com/rparrett/entytd/issues/1 and I'll make that a top priority for a post-jam update.