Oh and because I wrote it here, too. Storing only didn't work because of Java 8. Same thing with the bug which made it necessary to reset before playing. Should be all good now :)

Thank you for the link. I don't understand much from it though. Should I stick with Java 7 or is there an (easy) way to make it work in Java 8? I just read through some of the changes Java 8 brings, but if I understand it correctly, then it doesn't change anything in Greenfoot for me, right?

Oh, what I forgot to say. I increased the detonation time by 50%. So now, you can actually place some bombs without killing yourself. Also changed the next level animation a bit. Storing still doesn't work for some reason and it starts with a white screen. Just reset once to be able to play.

I have no idea why, but you need to press 'reset' once to start the game... At least I am only getting a white screen when open this website.