It is a game where everyone simultaneously plays a unique number face down card a la Category 5 (6 Nimmt).
There are 5 suits arranged in a circular pattern. The idea is you score the points based on the first person to hit their number traveling clockwise after the current number, e.g. if the colors are Green, Blue, Red, Yellow, Orange, Green, Blue, etc. and the current target card is Orange 6, then the first number after orange 6 wins a number of points equal to the interval. For example, orange 7 would win 1 point, but if it were not there and Green 1 were next closest, it would win 5 points. If the next closest card were orange 5 (unlikely but possible), it would score 49 points.
Each player also always has in hand a Shit! card which cannot score, but playing it is the only way to get another card in hand. Strategy comes from watching when people play cards and how many they have left. Time it right and you can play while everyone else is drawing for monster points.
It's a fun 20 minutes. The rules are in English.