Players each pick a card with several possible categories, and select one that becomes their "category" for the game. Before the game is announced, the players go around twice to say what their category is, after which everyone's responsibility is to remember everyone else's categories.
During the main phase of the game, cards numbered one to eight are dealt out to each player. Whenever a card JUST placed from the deck matches one on the table, the two players whose stacks have the matching numbers go head to head: whoever says something from the other person's category first wins both cards (each category member may only be used once). There are also a small number of "Rambo" cards, which when played start an all-player race to say the "Rambo" player's category first (including that player). The winner of the Rambo round gets the Rambo card.
There are various other rules to ensure that no players reveal others' categories, help other players, etc.