Doom is bountiful beyond all reason. It is truly the gift that never stops giving. Its base campaign is enough as it is, and the pursuit of its mastery was a crucial element in speedrunning's infancy, but with WADs it can simply never end. Doom harbors a level editor robust enough that it has never stopped seeing heavy use. It's not even just a level editor, that's what Wolfenstein has. Doom has full-on mod support, something that was totally unheard of. Equally unheard of is deathmatch, an ONLINE PVP multiplayer mode the likes of which no shooter had seen before.

It's a fast, frenetic, inventive embarrassment of riches, the likes of which we never truly deserved.