Collect shells and build sandcastles before the tide comes in.
Strand Unter is a three-dimensional family game in which everyone places their castles in the sand so that they are close to the water, while trying to stay out of the way of the tide.
Plenty of shells can be found in the ankle-deep sand trenches, and those who collect enough of them in competition with their fellow players can build a total of four sand castles. These castles differ in size, value, and required building material. In the end, the best castles are those that escape the approaching tide by a hair's breadth...
—description from the publisher