Frenzy

After generating financial success for Stern Electronics with Berzerk, Alan McNeil set about creating a sequel to the game, and it was entitled Frenzy. Frenzy keeps the basic theme of Berzerk, pitting a lone human player against a never ending army of robots through a never ending maze of chambers.

It expands on the basic premise by providing not one, but two different styles of robots, destroyable walls, shot reflecting walls, and a no longer invincible Otto named crazy Otto. Every fourth chamber contains a special feature that will sometimes alter the situation in the room if shot at.

Frenzy never achieved the same level of success and notoriety of its predecessor, possibly due to its increased difficulty. Coleco purchased the rights to bring Frenzy home to its home system, ColecoVision, but it never made an official appearance on any other console.

Differences from Berzerk

 * In Berzerk, the walls are all solid. In Frenzy, some of the walls of the maze are composed of dots which can be shot. This opens up strategies such as blasting a hole in the side of a room to escape when in trouble. The solid walls, on the other hand, now reflect shots. You can trick robots into killing themselves by standing on the opposite side of a reflective wall and letting them shoot themselves. The only wall that simply absorbs shots harmlessly as in the original is the closed door that appears behind you when you enter a new room.
 * Neither type of wall is electrified, you can touch them without dying. On the other hand, you also can't kill robots by tricking them into walking into the now-harmless walls. In addition, it is harder to die by touching the robots, but still possible. Their shots and the blast radius from an exploding robot can kill you. There are two types of robots: skeletons and tanks. The two types have identical AI, but the skeletons are more difficult to shoot from above or below because they're so thin.
 * In Berzerk, Evil Otto was invincible. In Frenzy, where he's known as Crazy Otto, shooting him once changes him from a smiley face to a 'neutral' face, and another shot converts him to a 'frowny' face. Another shot kills him. However, killing Crazy Otto makes him a little bit faster the next time he appears, which is usually immediately.
 * Every four mazes, a special chamber feature appears. Each one has a specific effect on game-play for that one room. The Power Plant and the Central Computer are surrounded by walls made entirely of 'dots', while Big Otto and the Robot Factory are surrounded by reflective walls with only one breakable 'dot' in the corner, making them more difficult to hit. In order, they are:
 * Big Otto: If you kill Crazy Otto, not only does he immediately respawn as usual, but Big Otto sends four more Ottos at you, all moving at top speed.
 * Power Plant: Shooting the power plant once will disable it, and all robots in the room will stop moving.
 * Central Computer: Shooting the computer will cause all the robots to start moving and firing erratically. While they're in such a state, the walls can kill them.
 * Robot Factory: The factory will continue to spit out additional robots while you're in the stage, taunting you as it does so. Shooting the factory has no effect.
 * Like the Robot Factory, shooting Big Otto has no effect. Big Otto starts out with closed eyes and a neutral expression, but his expression changes to one of rage, with glowing red eyes and a frowning mouth, when you kill Crazy Otto. He also smiles when you die, though his eyes remain the same as before, either closed or open.
 * Finally, the robots are nowhere near as talkative. They only speak in a few specific situations. They say 'Robot attack!' when Crazy Otto appears, 'Charge attack to kill destroy!' when you kill Crazy Otto and he respawns, 'The Humanoid must not destroy the robot!' when entering the Big Otto room, 'The Humanoid...' when shooting the Central Computer, and randomly alternates between 'A robot must get the humanoid' and 'A robot, not a chicken' when the Robot Factory dispenses a new robot. The constant background chatter of the original game is gone.