Interesting how different people arrive at similar ideas. Many years ago I created a retro-like "virtual computer" in Java, called simpleJ, to let teenagers learn how to program by creating simple arcade games. It also had an IDE like environment, with a step by step debugger that could draw a diagram of run time data-structures (arrays, linked lists, trees, etc.), a tile editor, a sprite editor, and a even a book teaching you how to program a video game. You can take a look at it at http://simplej.com/ (in Spanish).
