I'm not getting the blue tint bug on this game, but I've found it frequently before—it's just that firefox lets you select the game for some reason. the blue tint is just the selection highlight. So a lot of mouse-controlled unity games just have this problem in firefox, it's annoying, but not game-breaking. Sometimes I can double-click to get it to go away, but it usually comes back within the next few clicks. Anyway, super fun game though! i love the lil goblin character :)