"Since the start of the zombie war, Teknoboom developed the most dangerous handheld gun known to man. While half as effective on larger targets, the Zerfallen utilizes the extraordinary JOLT technology to vaporize any number of lesser zombies instantly."
The Zerfallen is a Energy rocket launcher that was released on April 28, 2016. It was initially found in the "Easter Patch", although without any stats. On April 22, a user hacked into the game's files and was able to leak the stats of the presumably upcoming gun. The user posted the weapon stats on the forums, although the post was taken down approximately 11 minutes later.
The gun seems to be very strong for its classification. However, this comes at the price of having only 2 shots in the clip, alongside with a huge 80% movement penalty. The Zerfallen appears to launch a 6 Meter diameter blast of energy that looks like a bloated version of the impact of the Torment but it's blue instead of red. The blast radius also appears to be very huge. It also has the ability to paralyze/pin zombies in place (Also making them unable to do normal melee attacks) that survived the shot, however, this doesn't work on some bosses like Loaderbots, Zombie Mech, and Necrosis Spawns. Adding a base core is extremely recommended for an extra ammo. There's a bug on this weapon where if you fire the weapon and there's a puke worm present in melee range, the orb just instantly explodes. The orb is capable of damaging an enemy twice if they are near a wall, once from getting hit by the orb and the explosion damage when the orb hits the wall. It costs 400 NK coins or $39.99 USD, making it one of the most expensive weapon in the game, along with the Torment, HIKS 888 CAW, and the CM 000 Kelvin. Zerfallen appears in the store along with Torment and CM Proton Arc
Initially, this weapon had 50,000 damage, which was changed to 55,000 on April 26, 2016, and then nerfed to the 35,000 damage we have today.
In the description, it says that the Zerfallen uses JOLT Technology. This is probably referring to the Jolt Ship that destroyed Thera on the mission Vaccine, suggesting that the Zerfallen uses similar technology.
The orb the Zerfallen fires can travel through the subway's doors on Vaccine, and possibly the doors where the Vaccine itself is located although this has not been tested.
It is the second heaviest weapon in the game, the heaviest is HIKS M1000 (Championship gun)
"Zerfallen" means "Decay" in German
SAS Zombie Assault 4 CM Proton Arc and Zerfallen GUN UPDATE