Tommy Pickles' father has been sent to Europe to fix a broken robot at EuroReptarLand and has decided to bring his family and friends with him. In the Nintendo 64 and PlayStation versions, the player can choose between six playable characters throughout the game: Tommy, Chuckie, Phil, Lil, Angelica, or Kimi. There are approximately 16 levels, as well as hidden bonus levels, in both single and multi-player mini-games. The object of the game is to collect enough gold Reptar tickets to buy the Reptar Helmet that controls a Giant Robot Reptar. Tickets are earned during mini-games, and can also be collected throughout the park. During most mini-games, the player plays against ninjas; aside from mini-games, the theme park is otherwise devoid of other people.
The Game Boy Color version features eight side-scrolling levels and seven mini-games, while the plot involves Chuckie and the other children searching the theme park for a princess to become his new mother. The game includes Dil as an additional character, unlike the home console versions. Each mini-game is played with a different character. Many mini-games include a time limit during which the player must complete the game. Tickets, earned by playing mini-games, allow the player to advance to new levels, which are accessed via an overhead map of the park. A password is provided after the completion of each level, allowing the player to resume the game at a later point.