From the Publisher:
Ripple Rush is a flip-and-write game. You draw a card with a number and a color on it. You then write the number in the column of the same color on your sheet. If you draw a number that you cannot place, each other player can write the number on their sheet. When you complete a row, you get to place a bonus number. At the end, you score points for each color equal to the longest length of filled in boxes.