Playing Doom 3 over a network co-operatively?

[King Mustard]

Is it possible to play Doom 3 and/or ROE over a network co-operatively?

[Mudman]

Sure is! But you'll need a mod for it to work. These two are the two popular ones I know of:

http://www.d3opencoop.com/

And

http://lms.d3files.com/

Enjoy!