pCube (pro Cube) is a mod for the FPS Cube. Cube has some bugs and is not anymore supported by it's developers. So pCube aims to fix those bugs and provide a few additional features like CTF, server-side maprotation, etc.
Would have been great if they'd included license information, but they haven't, so for me it's unusable. Pity, hate it when good code has to go to waste because programmer didn't think to leave a clear license. I'll have to use the original Cube source instead. The sourceforge project page says pCube is zlib/libpng license, but that clashes with the license of the original Cube project (which has an additional clause) so this must be incorrect. I'd be happy to change this to a thumbs up if they fixed the missing license issue.