I've seen it, but it's basically just Minecraft Classic, which was never very resource heavy. The reason it fits into 4MB is probably because a much smaller area of the world is loaded at any one time, which is fine for such a small screen, but on a larger screen it just won't look very good with a short render distance. It's still pretty amazing though since Minecraft uses 100s of MBs even with a short render distance.ok, yeah. especially the RAM argument I hadn't really thought about.Oh it is. The large open worlds require a lot of GPU power and RAM.
You should check out the DS version, its an amazing achievement. How they managed to fit so much of the game into 4MB's I will never know.