Let's meet the Gnomon deck

Single Cards (characteristics) The deck features three characteristics with three options in each:     Pattern - Filled, Partial, Hollow     Color - Red, Green, Blue     Shape - Circle, Square, Triangle     Each of these has a distinct design to the card that is hard to mistake for any other, even at a glance. Each is also represented in the top left margin of each card by a single letter, the first of each option; these are also in a distinct vertical position, in the order shown above. In addition, there is an icon above those.  There are four of each characteristic, producing 36 Singles overall.

Complete Cards The Gnomon deck also has Complete Cards which have one of each characteristic on them, so a combination of Pattern, Color, and Shape. Now, the design incorporates all three characteristics, as well as having the same type of initials and icons in the margins, this time three initials vertically. There is only one of each possible combination, producing 27 Completes overall.

True/False The Gnomon deck also has matched pairs of True and False cards, which may serve further duties for scorekeeping or simply to represent opposites. True cards feature a unique color image on the face, while False have the same image in black and white - again, easy to tell apart from all other cards in the deck. They also have 'TRUE' or 'FALSE' in the top left margins, but no icon. There are ten of each, producing 20 True/False cards overall. This makes a full deck of 83 cards.

In Play