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.

I didn't use any images. They are created with the methods provided by GreenfootImage. I only looked it up how they should look. However, the background is an image after I created the world with wall objects and give them different images, but dropped that idea, took a screenshot of that, use it as the background and don't have a wall class anymore. The size is the original size (the pixels are just smaller/not so far away from each other) Probably it could also be twice the size to still fit on everyone's screen, yes. Usually I think smaller is better than too big though. Yes, you can move in all direction even though there is a wall, that's true. I still don't know how exactly the original movement worked. I mean in the article they talk about cutting corners and that even professional players don't always do that perfectly, but if you only click once and then click once again for the next direction you want to go at the next junction far away, it will always cut corners perfectly...

You mean a link to the original Pac-Man game in the gamasutra article I put into the description? Well, the original Pac-Man game was played into one of those "cabinet's" (there are also pictures of them in this article). There are a lot of emulators and copies of the game you can find, but I don't think that Namco published the original one in the internet.

I guess you changed the code of the class. You added at least four lines of code. The original one works without errors. What did you change (for example in the act method)? It would probably be the best to open a new discussion with a link to this scenario instead.