Fuck it. Just make Granatball X.
That would be interesting. I love Granatball. Make a symmetrical map, both teams get GDI buildings with Nod turrets, give the buildings a certain function like spawning bots, "creeps" if you want to and then BAM give everyone slowly traveling instagib grenades. Slap on the UT announcer and we got ourselves a masterpiece.
Guess it would need a lot of work though...