Gaming Union writes "During a demo of Aliens vs Predator (AvP) today at GamesCom, some more information was revealed about the single player campaigns, specifically their length.
In AvP, there are essentially three campaigns: Marine, Alien, Predator. Each campaign is said to shed light on to an overall story arc, so playing them all is effectively necessary to understand all of the plot. Each campaign doesn't seem like it will be overly long though, as all three campaigns seem just longer than a normal game combined."