As I mentioned, I don't know how the original movement works with the problems I wrote here in the comments... I could upload the source. However, it is mostly in German, so I don't know if it would help.

After removing all objects, a scoreboard should appear. If it does not, then your storage isn't available (= this will show you a red screen: http://www.greenfoot.org/scenarios/12380). For me (also using IE), it works fine.

Is there any way to set it back to default? If I want to use it in one world (at least similar as how you have it), but change from that world to another, how to I get the original cursor back (without clicking on reset and set the world manually)?

It's actually a cool idea! Maybe you could try to prevent too many red pieces to spawn one after another because then you have no chance to survive.