The zombies are on the loose. Supplies are getting scarce. It's every man for themselves. But in such difficult times, people will band together into gangs in order to increase the chances of survival. It's in saying that that Warlord Games announces some new gangs for Project Z: The Ops and the Bikers.
As you can expect, the Bikers are a rather fast group, able to rush in and get objectives in quick order. They're also well-armed, even carrying a bazooka into battle. They're not the most highly-armored group, though. So if they get bogged down with zombies, that might just be all they wrote. As for the Ops, ok, so maybe calling them a "gang" is a bit much, but they're also very well armed, but also have years of training and body armor on their side. So they've got that going for them. You want efficiency? You want the Ops.
Ops Preview Source
Biker Gang Source