Wolfire made an unfinished prototype using the proprietary Unity engine for the private Humble Bundle Mojam. You can watch thic entertaining, commented timelapse video to find out more.
If you're interested in the ongoing development of The Broadside Express, follow this thread.
another video: Mojam Art Overview
Art assets have been released into the public domain (.zip here), with a few exceptions mentioned here (music and sand texture).
Blender import of a few .obj files from the .zip for testing
Included are 47 .obj 3d models, 41 .png/.tga/.psd images and 7 .wav sounds.
If you're interested in the ongoing development of The Broadside Express, follow this thread.