It's impossible, to get the Zeus cannon, you need to get a thundergun from a random gun box, then you need to pack-a-punch it. You can't earn enough points on the first round, to unlock rooms and get the weapon
The Zeus Cannon is the strongest weapon against zombies and the most effective for clearing a massive horde or when you are trapped and cornered.
you cannot upgrade the Zeus canonn because the Zeus cannon is the upgraded version of the thunder gun and you cant upgrade a gun twice
yes the cosmic silver back shows up at lv.70,72 or 73 and you have to defend yourself. the cosmic silver back is unkillable unless you have a Zeus cannon and raygun.the rounds last 5 minutes and then the next round starts.
There is the Thundergun(Upgraded is Zeus Cannon) and a new freeze gun, a.k.a. death to zombies I don't know too much about it.
Round 30 SOLO on Kino Der Toten, 27 on "Five", just remember to play with two people when trying to get on the leader boards because solo doesn't count towards the leader boards. i had Porters X2 Ray gun and Zeus Cannon, Whats your highest?
round 103
Round ninety-nine is the last round.
My highest round was 56
the m16 and the g11 are both three round burst guns on call of duty black ops
You go to a cannon and blow up the stuff on the runway
Porters x2 ray gun and zuse cannon
it keeps on going