M is regarded by many as one of the best offerings in the trick-taking genre. Players reveal cards to declare their bids: the highest bidder becomes the Crown and the second highest bidder is the Shield. Both the Shield and Crown choose a trump (either number or suit), then players try to capture tricks to score the most points. The Crown chooses a partner and tries to cover the bid to score bonus points, while the Shield and remaining players seek to stop the Crown from reaching their goal.

The deck contains 60 cards in five colored suits; each suit contains cards numbered from 0 to 9, with two each of the 1 and 7 cards. Cards also have 0, 1, or 2 triangles printed on them to show the point value of that card.

M & more: Revised Edition features "an adjusted rule set that makes it easier to get into the game". Vintage M rules will be available online, along with rules for other games that constitute the "& more" part of the title.