Tichu took much of its rules and mechanics from Zheng Fen. It is a partnership climbing card game, and the object of play is to rid yourself of your hand, preferably while scoring points in the process.
The deck is a standard 52-card pack with four special cards added: dog, phoenix, dragon and Mah Jong (1). When it's your turn, you may either beat the current top card combination — single card, pair of cards, sequence of pairs, full house, etc. — or pass. If play passes all the way back to the player who laid the top cards, they win the trick, clears the cards, and can lead the next one. The card led determines the only combination of cards that can be played on that trick, so if a single card is led, then only single cards are played; if a straight of seven cards is led, then only straights of seven cards can be played, etc.