Think about the condition(s) that would be true at the end of the world. How could you express this in code? When you move right (for example) it probably says something like : if (Greenfoot.isKeyDown("right") { // movement code here } So, you'd need to change that to only allow movement when the edge condition isn't true. if (Greenfoot.isKeyDown("right") && ! edge_condition) { // movement code here } Replace 'edge_condition' with a suitable condition. Probably this condition is a function of the current position and the width of the world.

Thanks for your reply. I understand what you mean, but how do I make a condition like this if the background is a long image? Thanks in advance.

Well, how does the code keep track of the position within the world (i.e. the amount the background has scrolled)? I'm not looking at the code right now, but I assume there is some variable somewhere which tracks this?