As someone who knows absolutely nothing about CPUs, is this CPU design _that_ good, or is it just the fact that Notch made it that's generated all this hype?
What's (potentially) revolutionary about this game is the deep rooted support for emergent gameplay. A telltale sign of a great game is that players themselves, in exploring the game, find new and interesting things to amuse themselves. Minecraft is an obvious example, with hundreds (thousands?) of public servers dedicated to varied pursuits.
A different type of example could be EVE, where the rise and fall of corporations is gameplay not written in by the devs, but gameplay created by the players. Any game that has developed a professional gaming community could also be lumped into the category of having emergent gameplay, since there is an entirely new game mode (spectating) created by a community surrounding the game.
When I look at 0x10c, and know that I'm going to have complete control over a CPU in game, and this CPU will be the basis of my pursuits in the game, I know that there will be interesting things to be done. This is because there's such a strong focus on allowing players to create their own gameplay. No other game (that I know of) takes its players' creativity seriously enough to rest so much of the fun on their shoulders.
Having Notch to hype the game certainly helps, but helping to create this world is alone an exciting prospect.
I think it has very little to do with the design of the CPU itself but rather the unprecedented introduction of a functional CPU being emulated and usable/programmable within a game itself.
The fact that it was Notch gave it visibility, but I think the following is more than just design or cult-of-personality.
Simplicity is extremely important. A lot of emulators appeared the same day that the spec was released. That not only needed people who wanted to implement the CPU, but also a spec that could be implemented in under a day.
There's a bit of Benevolent Dictator effect here as well. It's not that the system is the absolute best, but it's something that people can target for interoperability. Someone can write a compiler and someone else can write the emulator.
As an aside, I find it entirely plausible that these restrictions are, if not designed for, at least desired in the design.
As they make the work of a compiler harder, they promote coding in assembly to get faster code. This, on the other hand, leads to lower code quality (as avoiding gotchas and dealing with corner cases correctly is a lot easier even in c than in assembly), which creates more "drama", which is good for gameplay.
I don't think the 6502 had #1, or at least not in an easy way. Accessing, say, the second element from the top of the stack required you to copy the stack pointer to the ?X? register, then use that to index into the stack. That works, but is cumbersome.
