Loco! is a small filler by the good Dr. Knizia. It's hard to believe this is by the same mind that brought us Tigris & Euphrates, but he's nothing if not eclectic.
In the small package you have 30 cards running from 1 to 5 in five colors, plus a Loco! card in each color, which counts zero points.
There are also 25 small chips in each of those same five colors.
The game is dirt cheap, so for the money the components are great.
First you separate the colors into 5 piles, which are put in the middle of the table.
Then you shuffle the cards, remove two (or three depending on players) randomly and without looking at them, and then deal the remaining cards to the players.
A turn is simple: You pick a card and play it next to the color-corresponding pile of chips. Then you grab one of the chips from the table (it doesn't have to match the card you just played). The card goes on top of any previously played cards from that color, and now represent the worth of that color.
Each Loco! card is worth zero, and before playing one you have to yell out Loco!, otherwise you can't take a chip. (We don't play with that silly rule.)
The game ends when the sixth card of a color is played. You count up each chip in front of you, and the worth is based on whatever the top card is for that color.
The winner is the person with the most points from those chips.
It's not brain-burning, but the choices are still interesting and fun--plus the removal of cards lends some great uncertainty. And it plays very quickly. It's a great filler for a great price.