It looks like there is a problem related to the filenames of images. Java is case sensitive in general, but because Windows (and other operating systems) are not case sensitive about filenames, it might work on your machine, but when uploaded to the Gallery it breaks if the cases are not correct. So, check that the names of the images that you use in the code is exactly the same as the filenames - including upper and lower case. In this case it is the file "savedata.txt" that is the problem.

To see error messages you have to open the Java Console. How to open the Java Console depends on the browser and OS you are using. Maybe you can use the hints here: http://mindprod.com/jgloss/console.html (not sure if they are up-to-date though).

The problem with the directory names sounds like a bug in Greenfoot that should be fixed. I've created a bug report for this. Thanks for reporting it qnanqing!

Maybe there should be a delay from when you start the game till the aliens start firing. Sometime I'm placed right next to an alien, and don't have time to move before it shoots me.

Hehe, thanks. Or maybe I have just been caught by this problem a few times too many ;-) I like the new level. Keep up the good work!

It looks like the problem is related to the filenames of images. Java is case sensitive in general, but because Windows (and other operating systems) are not case sensitive about filenames, it might work on your machine, but when uploaded to the Gallery it breaks if the cases are not correct. So, check that the names of the images that you use in the code is exactly the same as the filenames - including upper and lower case.

It doesn't start anymore. Looks like it might have to do with some of the images that fail to load. When you export to the gallery, the filenames are case sensitive!

If I understand correctly the goal of the game is to collect the ball and then move to the red cross? But, the game ends when I reach the ball. Maybe that should be fixed before making nicer graphics and bigger levels? But you are probably working on that right now ;-)