Each player starts out with one face up card and players do not get a hand but rather keep cards they collect in front of themselves. There are 7 colors, 9 cards of each color, and some wild cards and "+2" cards to mix up the action a bit. At the center of the table, for every player playing there will be one row. Each rows start out empty and slowly fills up with cards--up to 3 cards maximum per row. On his turn a player can either
A.) draw a card and put it in any available row
B.) take a row of cards and add them to his own.
When a player has taken his row, other players continue playing in turn until everyone has taken a row. Then the process begins again until 15 cards before the deck is depleted and the 'end of round' card is drawn. Then players finish that round and a scoring occurs. The player considers his hand and figures out which three colors are represented by the highest numbers of cards. In a three player game, for example, PLAYER ONE may have collected:
6 blue cards (nice job! any more than 6 is worth nothing)
5 gray cards (good, good)
5 pink cards (excellent, rare to get three big sets like this)
-----ANYTHING FROM HERE DOWN IS NEGATIVE-----
3 green cards (oops, don't want a powerful 4th place color!)
1 brown card (bad, but not too bad)
His best three colors are blue, gray, and pink and, after consulting the tiny table that comes with the game, he determines they are worth 21, 15, and 15 respectively. Any other collections count against him. His green is worth -6 (ouch) and his brown is worth -1. So his score is 21+15+15-6-1 or 44--a great score actually. If he won some '+2' cards, he can go ahead and tack those onto his score.
Coloretto is a very simple auction game disguised as a card game. The most tense and joyful moments in the game come when a player is trying to decide between taking a mediocre row and drawing a card. Like Ra and some other auction games, there are things you want, things you don't want, and things you are ambivalent about. In Coloretto, determining what you will pair together for the next player to mull over creates the fun for this game.
Important to remember: the cards you want will help you much more than the cards you don't want will hurt you. The 5 steps forward and 1 step back feel to it makes for a fast game with generally tight scores if people are watching themselves.
Players familiar with Knizia's Africa may, after a few plays, begin to figure out that they should be shooting for a certain average number of points per action in that game. In Africa, a good turn yields about 5 points. In Coloretto, later actions are, of course, more valuable as your card stacks get higher, but that average point per action goal starts at about 3 and ends at about 5. At the end you find yourself getting the most valuable stuff, but also the most painful stuff.
I enjoy this game. I would say that among light games, this one is a quite appealing 8/10. Our second full game took us 40 minutes total for 3 players. Luck plays a major role, but there are plenty of chances to feel redeemed for a wise decision. I highly recommend playing wildcards immediately instead of waiting for the deck to end and applying them then. For really competitive and groan-filled games, try only scoring the best TWO colors.