When the game starts, each player is randomly assigned one card - a different color for each player.
Object of the game is to collect as many cards as possible in up to 3 colors (which will score positive points at the end of the game), and minimize collecting cards of additional colors (which will score negative points at the end of the game). Which colors are positive/negative is only determined at the end of the game.
Players perform one of the following actions each turn:
- draw a new card and put it in one of the rows (there are as many rows as players)
- take a row of cards
When a player takes a row, their turn is skipped until all players have taken a row. Then a new round starts, and players can again fill rows with cards.
There are seven colors of chameleon cards (six for three-player games) and three kinds of special cards: Joker (rainbow chameleon), "+2" and "Last round". There are nine cards of each color in play, three jokers, ten "+2" cards, and one "Last round" card.
When a player draws the "Last round" card, the game finishes at the end of the current round. The player who drew the "Last round" card puts it away and immediately draws another card.
Scoring: Each color scores according to the chart shown (1/3/6/10/... points for 1/2/3/4/... cards in that color). However only THREE colors score positive points (the largest three). The remaining colors all score NEGATIVE points according to the same chart (e.g. -1/-3/-6/... points for 1/2/3/... cards in that color). Any joker (rainbow chameleon) cards are automatically added to the largest set. "+2" cards simply add 2 points each.
The winner is the player with the most points at the end of the game.
Difficult scoring mode: Set scoring is no longer strictly increasing. Instead, each set scores 1/4/8/7/6/5 points for 1/2/3/4/5/6+ cards. This arrangement can lead to usually desirable wild cards being a liability for players.