"The source to a Java-based Mario clone that is very different to Mario." you mean. Mario is over a decade older than Java. The NES did graphics in a wildly different way than is being done here.<p>And we're using Box2D physics and floating point math :p<p>The thing to note here is that you can make an incredibly entertaining game with a few hundred lines of code, and you can do it a lot faster than in the 80s, less memory and speed constraints, looser types, easier higher level languages.