Biff Fraggar is a project to make a FOSS replacement for the Ultimate Doom and Doom 2 IWADs, in a similer vein to Freedoom, but without a focus on compatibility, and moreso just to make a free game, so as to not reinvent the wheel.
Biff Fraggar's assets are licensed under the GPL, with use of BSD and CC0 licensed assets. The project makes use of Freedoom's DEUTEX tree as a basis.