J.J. & Jeff, originally Kato-chan & Ken-chan, is a side-scrolling platformer that is filled with humor and secrets. The player is encouraged to experiment with their surroundings, using their main character's kick and jump moves to uncover secrets in the environment, such as power-ups that spring out of trash cans when kicked. There are doors that take the player to special "skit" cutscene areas that often restore the player's health.
Kato-chan and Ken-chan, the characters in the Japanese version of the game, are based on Cha Kato and Ken Shimura: two comedians that hosted a variety show named Kato-chan Ken-chan Gokigen TV that featured skits, satirical discussions and a segment where viewers could send in humorous home videos before America's Funniest Home Videos borrowed the concept. The original Japanese version of the game was far more scatological, and featured brief nudity. Much of this content was censored for the US version.