A good starting strategy (4 players) is to go down to the second level, but do not open the barricade on the staircase. Instead, have each person buy a sub machine gun off the wall and each of you guard a window on the upper level terrace. Every once in a while, let a few in to grab ammo boxes, or 2x points and stuff. The good thing about this is that ammo is always close by on the walls if you need it, and you can go down to the second level as early as lvl 2, and have around 10,000 each before you even open the basement to grab the random box and pack a punch...we've stayed on the second level as far as lvl 10 before opening the barricade...easy money!
Hi i'm snowkid of the second strategy..thanks for posting the strategy here..the strategy it's good because in that floor the zombies that explode they don't came