I'm currently migrating the master branch from the original source release over to BFG so check out that branch for an actual working system.

idTech4.net

idTech4.net is a port of doom3 to C# and using XNA for rendering.

idEngine

This is the port of the engine source code.

Done so far:

• core system.
• file system (implements pak processing but currently does not load files from pak's).
• partial render system.
• command system.
• cvar system.
• console.
• resource loading (decl, materials, user interfaces, scripts).
• user interface rendering and interaction code.
• partial game code.
• content management through XNA pipeline.