This project is very interesting for a number of reasons, I'm surprised it hasn't received more attention. If I were Mojang I'd be quaking in my boots right now.

No single factor has been exclusively responsible for Minecraft's runaway success, but an undeniable essential contributor has been the extensive modding community which has formed around the game. The nature of the game as a sandbox makes it highly amenable to modding, and by writing it in Java -- a language easily decompiled and recompiled, for modding -- Notch (perhaps inadvertently) allowed this modding to take off, launching Minecraft into the stratosphere.

Countless clones of Minecraft have been attempted, yet none gaining any traction comparable to the original. Part is this phenomena can be chalked up to the first mover effect (though arguably Infiniminer was first), sure, but I'd argue the mod-ability of Minecraft is an even more important reason for its continued success. Mojang believes this too: jeb_, the current lead developer, has said he strongly believes a modding API is crucial for Minecraft's future, and its his #1 priority.

Seriously, if you've never played Minecraft before, the difference between "vanilla" Minecraft and Minecraft mods collectively (as in modpacks such as Feed the Beast) is like night in day. Many "mods" can be better considered as completely different games. We're not talking about minor tweaks and modifications, but brand new and compelling gameplay content.

Mojang is working very hard on cleaning up and refactoring and optimizing the code (never originally intended for modding) in preparation for an official mod API, anticipated by players and modders everywhere. But here's the kicker: what if someone else beats them to it?

For this reason, Voxel.js's focus from on developing a modular engine with plugin-able modules from day one is pure genius. Climbing over the wreckage of abandoned one-off clones, they sought to build something better, something sustainable. And it is working: even after only a month of hacking, Voxel.js already has several fairly impressive third party addons. Tree generation, solar cycles, terrain gen, multiplayer.. Not bad at all. And someone is even working on bringing in WorldEdit-ish functionality!

Yet modularity on its own is not enough. Several Minecraft clones already have plugin support, but nonetheless lack the player base of the original. In order to attract developers, modders, and players not only must the platform be architecturally attractive but accessible as well. Voxel.js fits the bill even better than Minecraft -- nothing to install, just go to a website in your browser, and begin to play. (Minecraft, as a Java app, could be played within a browser I believe, but especially with Oracle phasing out applets, I wouldn't consider it on the same level as modern JavaScript web apps).

So there you have it: the inherently attractive nature of an open world sandbox voxel game, an open and modular design built for the ground up specifically intended to be reusable, on top of the low-friction easily accessible platform of the web. As more modders begin to take note, I expect the snowball effect to kick in, and Voxel.js (or its derivatives, or its own clones!) could take off and become even bigger than Minecraft.

The why hasn't it? In fact, I attempted to develop a project a while back almost exactly like Voxel.js. JavaScript+WebGL+websockets+voxels+sandbox (an enticing combination if their is one). The technology just wasn't there at the time. The pointer lock API is mandatory for these kinds of games, and I'm pleased it has been implemented in Chrome by now (an other browsers soon) -- this demo works amazing well. Could use a little polish, but I could see myself playing this for real.

Perhaps my involvement with Minecraft modding and abundant familiarity with its limitations (as the author of this article brought up: decompiling...yeah) has led me to be overly optimistic of viable alter alernative platform. After all, Minecraft is more of a platform for games than a game in itself. There's no reason why someone couldn't build a better platform draw gamers and modders from Minecraft. Who knows, maybe Voxel.js is that platform.