The visual game “Plus and minus” consists of 72 cards with different images. Many of these images (48) are on transparent backgrounds, so that they can be superimposed to compose other more complex images, stimulating the child's creative abilities. By superimposing some images of trees, a wood is created. By superimposing the design of the rain or that of the sun or the moon, or that of the flight of birds, or that of a passing dog, etc. on the wood, the total image is continuously modified as desired.

In 1968 Munari published In the fog of Milan , in which he created images and suggestions declining the "seeing through" according to his personal creativity. The bright colors of the circus were preceded and followed by the milky opacity of the fog, an indistinct environment in which the figures are perceived as blurred in transparency but become clear as they continue to leaf through the pages. Two years later, in 1970, Munari returns to confront the theme of transparency and “seeing through” by designing with Giovanni Belgrano Più e meno .

Not a book but a game, made up of many images on transparent backgrounds, which can be superimposed and combined as desired, adding or removing cards. Square cards in which the color is in balance with the sign, and which together tell stories. Stories whose "glue" is the imagination of those who speak, with infinite suggestions available to create ever-changing stories. Immediately after Aconà Biconbì , Più e Meno continues in Corraini the discovery of the world of objects and artist's games, continuing the development of the special series dedicated to them. On the occasion of the centenary of his birth, the reprint of the most representative games by Bruno Munari is completed at Corraini: after Aconà Biconbì (1961) andPlus and minus (1970), ABC con fantasia (1960) is in fact forthcoming .