Well the past few days i have been playing the beta for the source mod Empires. Anyone who has played NS will already know the gameplay ( but empires is slightly different ) no build time before doors open, it has wide open areas and its not marines vs aliens ..... this is northern faction against __?__ empire but the whole concept of NS is in this game and though its still in beta for some 2 weeks now i just love it, has its problems with lag and all and minor glitches and more work to be done but i would recommend anyone with source to get this mod and try it out, mainly since source mods are in short supply right now.
http://www.empiresmod.com