Parsley Castle, an outer space kingdom, has been invaded! And strange beings are to blame. Playing as Rickle, a cyborg built by Dr. Cinnamon from Konami's Twinbee series, and several of his friends from other (mostly Japan-only) Konami games, your objective is to save Parsley Castle and once again bring peace to Konami World.

At the start of the game, the player can choose 3 characters that accompany Rickle on his journey. Those characters will appear in a cute super-deformed style.

During the game, once the first level has been completed, the player(s) will then traverse several levels inspired by the games the characters are from, like Castlevania, Contra, Gradius, and more. In addition, various mini-games will play from time to time (including one inspired by Frogger, Konami's first major arcade hit).

In addition to Rickle, players can choose between Simon Belmont of "Castlevania" (a holdover from the first game), Bill of "Contra", Fuuma from the Japanese title Getsufūma Den, Goemon of his self-titled series (best known to Americans as Kid Ying from The Legend Of The Mystical Ninja), and Upa from Bio Miracle Bokutte Upa, another Japan-only title. The player switches between the characters he/she has selected by obtaining pods that fly similar to the power-up pods in the "Contra" series. Rickle will then become one of those characters for 60 seconds (decreasing with damage).

In addition, like the last Wai Wai World game, two players can team up to save Parsley Castle together.