I recently had the opportunity to visit Kent University and attend a day with Michael Kölling (key figure in BlueJ and Greenfoot development and senior lecturer at Kent University) and play with the Greenfoot development environment. What interested me about Greenfoot originally is that it is a simplified game development environment (similar to Game Maker by Mark Overmars) but is in some respects more simplified.
Rather than using a newly created language (GML in Game Maker) Greenfoot simply interfaces with Java, and you actually end up writing pure Java code using the Greenfoot library. Despite this, Greenfoot is actually incredibly simple to use and ideal for small simulations/experiments or very simple games.
Personal dislike towards Java aside, The main difference in Game Maker and Greenfoot is perhaps the overall goal. Over the years Game Maker has distanced itself from the academic side and more to the amateur game development side, whereas Greenfoot remains purely for academic purposes. The original goal was to create a development tool which can be picked up easily, and interest high school students in programming through the practice of simple game development.
I don’t think Greenfoot will ever evolve into something like Game Maker purely because of it’s main goal. That said, it’s still a pretty cool tool if you want to learn code. It teaches you REAL code and not that sissy VB crap that they teach elsewhere. One other advantage perhaps is the ability to export projects. This means that after producing something you can export to whatever device Java supports — something that GM users have wanted for a long time.
Will I be releasing anything? Maybe.
See links below for Greenfoot and other resources.
http://www.youtube.com/watch?v=Tcwx-I6Arwk / Micheal Kölling @ googletechtalk