Thanks for the great feedback! Actually, our dev is colorblind and we tweaked the colors a bit so that he could see it (but he definitely had more problems when it was green vs yellow). But symbols are probably a really good idea, maybe we will add that in a future iteration!
Quick heads up: Sadly, the level "Gateway to Hell" is really a gateway to hell, that is that there is no solution. The good thing: It's very near the end, and all important mechanics are already on display in the levels before. Sorry :|
