Id get blank to add a battle feature.
Basicly you choose the amount of hours and a completion date.
Say i wanted to play near in a 1v1
I would select something like challenge near. 2 hours, end date (1 weeks time)
And points would be based on zombie kills, what zombies you killed and waves gained within the 2 hour period. A small clock would be somewhere on the screen like top right saying how many hours left until battle over.
100 points for 1 wave
10 points green zombie
5 points normal zombie
8 points ghost zombie
7 points screamer
Weapons collected could possibly go towards points but that is usualy about luck.
That way people can choose if they want to create new accounts to vs each other or use there main accounts. And it isnt souly the td's who have to organise everything. Plus having a feature like that would be similar to cws on pt were people can play each other in groups. Zed is a game were it is you (people) against zombies, i don't think having people vs people + vs zombies is a good idea.