Generations

From Doom Wiki

Generations is a modification for Quake II that integrates characters, levels, and enemies from Wolfenstein 3D, Doom, and Quake into the Quake II engine. The mod was halted in production after id Software threatened legal action because the creator of the project used graphics (as well as intellectual property) from previous id games.

Because the project was shut down, copies of the incomplete modification are difficult to obtain.