Quake: Mjölnir is an incredible community-made map pack inspired by an early concept for Quake.
Brutal Wolfenstein 3D is a Doom II mod that recreates Wolfenstein 3D and Spear of Destiny, with the awesome Brutal Doom style of gameplay.
Duke Nukem: Alien Armageddon is one of the greatest video game modifications ever made.
Perfected Doom 3 is an incredible modification that makes for a more enjoyable Doom 3 experience.
RealRTCW 5.0 is the definitive way to experience Return to Castle Wolfenstein. That’s all that needs to be said.
Thief 2X: Shadows of the Metal Age may not be official but it is an expansion worth playing through.
Star Fox EX includes a lot of new content and customization options. It’s huge, impressive, and a must play.
Call of Duty: United Fronts combines the vanilla game with the expansion and includes a ton of new missions. It’s a must play modification.
WolfenDoom is a mod that brings Wolfenstein 3D into Doom and, as a result, the gameplay that is carried over benefits from the features of the newer engine.
Die Hard: Nakatomi Plaza is terrible and the Improved Edition is a mod that changes some things for the better.