Risen3D

The graphic engine of Doom was set as Open Source. That decision was taken by idSoftware because they wanted to offer all Doom lovers the possibility to create their own version of the game. Own version? yes, because it's just the graphic engine that is free, not the content itself. It means that you need a file called IWAD to play the game. Those IWAD files contain the music, graphics, sounds, enemies, weapons and more.

Risen3D is a version of Doom that takes advantage of OpenGL technology to render the graphics. It can generate particle effects, models and high quality textures even better than the original ones seen in Doom.

FreeDoom is a version of Doom you can play by using Risen3D, because they need each other: Risen3D is the graphic engine that supports all the power of FreeDoom and other similar games.

Finally, configure lots of aspects of the game: mode, resolution, 3D sound, filters, skill and more.