Role in the episode
Jack Hammer was made to look like a tall, muscular man in overalls, steel-toed boots, and a hard hat. He wielded a sledgehammer that could convert into a jackhammer. Jack's internal mechanisms were so complex that they were installed in the control panel of an arcade game called Jack Hammer Hates Norrisville. The game was made to represent the actual city, and whatever happened in-game happened in reality.
Once Randy Cunningham was done, Howard Weinerman took up the controls. When Randy came face to face with the giant robot, he realized it was all a trap. Randy desperately tried to tell Howard the truth, but Howard disregarded it all as a way to distract him so he'd mess up.
Randy soon realized that letting Howard win was the only way to make Jack Hammer lose. Once Howard had beaten the score, Randy made a final request. Howard had Jack Hammer take a swan dive off the edge of a cliff. With the destruction of the robot, the game ceased to function.
Jack Hammer makes an appearance in the episode "Escape from Scrap City". He is no longer functional and has become the gate leading in and out of the arena.