Zandronum is one of the few ZDoom based ports with stable multiplayer support! Open Source for Windows, Linux and Mac.

Zandronum modernizes Doom, support of the OpenGL renderer. OpenGL, based from GZDoom, gives the environment a new fresh new look and also has support for 3D objects. Additionally, Zandronum has improved multiplayer support and dynamic servers. Zandronum supports up to 64 players, and clients can freely join any game servers at any time without having to wait for the host to launch a connection – – similarly in ZDoom. Also, Zandronum has an abundance of game modes. Such game modes can be a simple cooperative game, invasion, deathmatch, or maybe capture the flag with four teams. Zandronum is always active in both developments, community events, and the games hosted on various servers.

Link to Zandronum

Link to ZDoom

Link to FreeDoom

Zandronum requires Doom or Doom 2 IWAD file, there currently exists two methods to get the IWAD : First method is to purchase the game from, for instance, the idSoftware store, Steam, or Amazon.
Alternatively, one can download Freedoom which is free and legal.