The Decktet is a 36-card deck of cards in 6 suits. Each suit has 10 cards, a thing accomplished by most of the cards being double-suited. Most of the cards also have a name and illustration. The Decktet is a game system released under an open license.
It is available in a free print-and-play version. There are also printed decks available for purchase.
There are dozens of different games that can be played with the Decktet, many of which have their own entries in the database:
The Decktet Book (original edition feb 2010; revised and expanded edition oct 2011), includes an extended discussion of the history and structure of the deck along with rules and strategy notes for Decktet games.