like you see, it is currently in alpha-phase. but if you want to use it at the moment, you can download greenfoot 3d at http://metropy.net/greenfoot/3d/greenfoot.jar It can replace your greenfoot.jar (Windows: C:\Program Files\Greenfoot\lib\extensions). Dont worry, it supports the normal Actors too, so you can run your existing greenfoot projects like before. Lizense and source code, see http://metropy.net/greenfoot/3d/greenfoot.zip

Oh, I know what it is. It will replace the world's background to black for some reason... But it got super buggy and I got a ton of errors with one scenario I made. I had an actor with no image (so it would become replaced by a greenfoot) Could that be the error?

Actually, I found out that my worlds that I added a GreenfootImage as the background (using code and not an actual image file) that they have a black background instead of the coded background. Could you make a fix to this?

Also, with that one scenario I was talking about, their images were drawn with GreenfootImage code as well, instead of giving them an image file. That may be where I'm getting those errors.