Two days ago on our Discord server, we have released a build of Brickcraft/Rex Kwon Do - the unreleased Mojang and LEGO collaboration that never came to be. The build dates to the 28th of June 2012, around a month before the game's supposed cancellation (sourced from a Notch's tweet in July 2012 saying the game got cancelled). Tho I personally believe it may be one of, if not the last build ever.
You can download it here! To run the game, launch the server first and then you can launch the client to join with it. It features a working multiplayer!
Please note, that the game only works on NVIDIA graphics cards. To run it on AMD or Intel, you'll have to download a patched version of the shaders made by Grzesiek11.