Wow ok my typing is failing today. What I meant to say was: The reason this has a large file size is because the image I used for the background of the text is 1.1mb or so

I like it :) Things you could add to make it more playable that I can think of are: Add a scoring system, and also maybe add a timer (so you have to kill the enemies within a set time)?

I've just found that the panel.paint(g) code is causing an error when you click reset - This is only an issue if running it from within the Greenfoot IDE or via command prompt, as it still lets the world reset, it just gives you the error code - due to this it's not on my priority list to be honest

I've got one or two ideas for improving the efficiency of this further - I'll try it now, but it may be slow due to me being at college and the computer I'm working on is less than great...

That (should be) fixed now - it took me longer than expected as it turned out I was barking up the wrong tree for a while on the cause of the error - I'd misread the line of code it quoted in the error message >.<