Doomiverse

The Doomiverse is the universe of several id games.

Works

 * Commander Keen
 * Wolfenstein Series
 * Doom Series

Evidence

 * William B.J. Blazkovicz (Wolfenstein) is the grandfather of Billy Blaze (Commander Keen).
 * The Harbringer (Wolfenstein) threatens to return and eventually returns as the Cyberdemon (Doom).