beating a dead horse but maybe next lan this will find a place
Left 4 Dead Survival or Versus
Lets definitely try to get that game in at the LAN as a free time game and see how it goes. If it works well I definitely see no reason not to make it an official tournment at a future LAN. I just have no experience running a server but I know it can be difficult on a LAN as it keeps wanting to use the internet servers.