New code in Zandronum is released under a 4-clause license based on the OSI-approved and GPL-compatible Sleepycat License, with the addition of the 'No Endorsement' clause from the 3-clause New BSD License.

The source code is available on ODSN and all new code is licensed under a modified Sleepycat license.

Doesn't run on your flavor of operating system?.

Runes, new weapons, and new monsters for modders.

Supports announcers and skins for online play.Supports modern versions of Windows, Mac OS X, and Linux.Support for many Doom engine based games including Heretic, Hexen, and Strife.Useful features like a console, Quake-style key bindings, freelooking, and jumping.Choose between GZDoom's OpenGL renderer, or Doom's Software renderer.Support for large number of ZDoom and GZDoom mods.Modifiers, like Instagib and Buckshot, can be used to spice up any game.Cooperative: Survival, Invasion (or both!).Competitive: Team DM, Duel, CTF, Possession, LMS, Terminator, Skulltag.Client/server architecture: play and switch between games with ease.Here's why you should kill your time with Zandronum, versus vanilla Doom: Zandronum brings classic Doom into the 21st century, maintaining the essence of what has made Doom great for so many years and, at the same time, adding new features to modernize it, creating a fresh, fun new experience. Zandronum is a multiplayer oriented port, based off Skulltag, for Doom and Doom II by id Software. Welcome to Zandronum! Leading the way in newschool multiplayer Doom online.

Doom 3 open co op