Zandronum is a multiplayer oriented port, based off Skulltag, for Doom and Doom II by id Software.

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.

Here's why you should kill your time with Zandronum, versus vanilla Doom:

• Excellent online play
  • Client/server architecture: play and switch between games with ease
  • Supports up to 64 players
    • Wide array of gameplay modes
    • Competitive: Team DM, Duel, CTF, Possession, LMS, Terminator, Skulltag
    • Cooperative: Survival, Invasion (or both!)
    • Modifiers, like Instagib and Buckshot, can be used to spice up any game.
• Modern and beautiful
  • Support for large number of ZDoom and GZDoom mods
  • Choose between GZDoom's OpenGL renderer, or Doom's Software renderer
  • Useful features like a console, Quake-style key bindings, freelooking, and jumping
  • Support for many Doom engine based games including Heretic, Hexen, and Strife
  • Supports modern versions of Windows, Mac OS X, and Linux.
• Compatible with Skulltag mods
  • Supports announcers and skins for online play
  • Runes, new weapons, and new monsters for modders
  • Bots, and support for custom bots
• So much more!

• Official Website
• Community Forums
• Wiki
• Bugtracker

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. Practically, this means that Zandronum's source code is safe to use in either GPL or Doom Source License/Raven Source License/etc. source ports as long as the terms of the Zandronum license are satisfied.

The Zandronum license only covers Zandronum-specific code. Some source files contain additional notices of original copyright by their contributors.

See ZDoom license page for more details on other licenses used within Zandronum.