There are several colors of chameleons (depending on the number of players) and 2 kinds of special cards: Joker and +2. At the beginning each players gets randomly 1 card with a chameleon of different color than any other player.
On their turn players can : 1. draw a new card and put it in one of the rows (there are as many rows as players) 2. take a row of cards
When a player takes a row his or her turn is skipped until all players have taken a row. Then a new round starts, and players can again fill rows with cards. The game ends at the end of a round during which the 'Last round' card is drawn. The player who drew the 'Last round' card puts it away and draws another card.
Same colored chameleons are put into sets. The more cards of that color you have the more points it is worth. Only 3 sets bring you positive points, while every other set brings you negative points. You get to choose at the end of the game which sets will be positive (the BGA does that for you).
The Joker (chameleon with many-colored background) can be put into any set at the end of the game. The +2 card always brings you 2 positive points at the end of the game. It is never a part of a set.
The player with the most points wins.