Brilliant idea and well made
I love this, it's very well made and offers endless hours of playtime.
The editor is quite easy to use, could be a bit easier though. I didn't understand why you had to keep opening the menu, the stage could just be a bit taller and all the options could fit underneath. Here are a few suggestions for future versions (which you must make!):
-Graphical import option. E.g, someone can upload an image to photobucket then the game can read it. Having a small selection of graphics limits what this is capable of.
-Shooting option, would really broaden the type of games possible.
-Cookie saving of levels (I think most people wouldnt bother saving text files).
It's a great little flash, but I reckon there's still loads of room for improvement. Still 5/5 as it is though, nice work.