Ist da wer?! is a hide-and-seek game in which attentive children need to recognize what cannot be seen. The centerpiece of the game is a "thicket", that is, a large vertical container that represents a bunch of bushes. Inside this container are twenty wooden discs, two each of ten colors, and you can see these discs inside the thicket through 29 cut-out slots. However, the thicket is designed so that five of the discs will fall into grooves at the bottom of the vertical container, and the discs in these grooves will be hidden by a piece of cardboard underbrush so that they are not visible until you remove the underbrush during play. Ten animals in the colors of the discs are set up in the center of the playing area within reach of all players. Each player also has a stack of nine tiles that when placed together form a picture. Each round, one player shakes the thicket face down so that no one can see which discs are going where, then they stand the thicket upright on the table. Everyone then grabs for the animals that they think are hiding in the underbrush, that is, the animals that can be seen only once through the cut-out slots — or possibly not seen at all. Once everyone has grabbed all the animals that they wish to, remove the underbrush to see which animals are actually there. If you grabbed an animal that is in the underbrush, reveal one of your picture tiles, and if that animal is in the underbrush twice, reveal two picture tiles instead. If by mistake you grabbed an animal that is not in the underbrush, you must return a picture tile to the bottom of your stack. Keep playing rounds until one or more players have revealed all of their tiles, completed their picture, and won.