This Demo Map Makes Doom Look Absolutely Stunning - Doom Mod Madness

In Mute Witness Stand is a mod for Half-Life set during World War I. You play as British soldiers fighting in the trenches against the German army and an army of the dead, raised by experimental chemical weapons.

FreemanAPI - an easy-to-use API for implementing movement mechanics from the original Half-Life and Half-Life 2 in other games.

Pro Gen Mod: Unofficial Extension — an addon for Pro Gen Mod v2.6: Director Cut, which evolved from a Challenge mode update into a major expansion. It fixes bugs, refines generals, adds cut units and features, eliminates crashes on Challenge mode maps, improves balance, AI, and stability.

MetaDoom is a gameplay mod for GZDoom that combines elements from all parts of the Doom series into a single, insanely rich and dynamic mix. Weapons, enemies, and mechanics from the classic games, Doom 3, Doom 64, Doom (2016), Eternal, and even Doom RPG coexist and interweave with each other.

Halodoom is a total conversion that brings the Halo universe onto the Doom engine. It offers 16 weapon types, 13 maps (from Lockout to remakes of Doom II maps), 6 classic game modes with 72 possible mode combinations, and flexible Spartan customization.