These rules and UI references are based on Mahjong Soul

• Tiles
  • There are four of each tile
  • Each hand, there are ten tiles in the dead wall (top left) that will not be drawn
  • Suits - Man, Pin, Sou, valued 1 through 9
  • Winds - North, East, West, South
  • Dragons - Green, Red, White
  • Terminals - 1 and 9 of each suit
  • Honors - Winds & Dragons
  • Yakuhai - Dragons & Seat Wind & Prevalent Wind, see Open Yaku
• To win a hand, you need a completed hand and at least one Yaku
• A completed hand is one that has four triplets and/or sequences and a pair
  • Triplets are three of the same tile, e.g. 333 Sou or NNN wind tiles
  • Sequences can only be made from suits, e.g. 123 Sou or 345 Man
  • When you are one tile away from completing your hand, you are in Tenpai. The tile(s) you are waiting on to complete your hand are called waits
  • You either need to draw your winning tile (Tsumo) or have another player discard it (Ron) when you are in Tenpai
  • There are some rare exceptions to hand composition, see the various Yaku
• A Yaku is some criteria on the composition of your hand to make it qualified
  • The easiest way to get a Yaku is to not make calls and keep your hand closed. This enables Riichi which is a Yaku on any hand in Tenpai regardless of exact composition. See Closed-Only Yaku
  • Making calls may make your hand easier to complete, but reduce the value and restrict your Yaku options. See Open Yaku
  • There are also some very lucky or difficult Yaku options. See Lucky or Difficult Yaku
• Calls
  • There are some calls you can make to take other players' discarded tiles
  • Making a call opens your hand (except Concealed Kan)
  • After making the call, the tiles will be set aside and revealed to all players. They are locked in and cannot be changed
  • After each call, you will discard a tile because you chose to skip your normal draw to draw another player's discard
  • Chii - You can call this when the player to your left discards a tile that you can make a sequence from
  • Pon - You can call this when anyone discards a tile that you can make a triplet from. This may skip over other players
  • Kan - You can call this when anyone discards a tile that you can make four of a kind from. After calling Kan, another Dora indicator is revealed and you draw an extra tile to preserve your hand size
  • Concealed Kan - If you draw the fourth tile, on any of your turns you can call Kan. This does not open your hand, but otherwise works like a normal Kan
• Once you have won your hand you receive points from your opponents based on its value
  • A rough rule of thumb is you get 1000 points for each Han you had
  • If other players called Riichi, you take their 1000 point ante. See the red dot stick count in the top left under the Dora indicators
  • If the dealer (East seat) wins or draws, 300 point bonuses start stacking up. See the black dots stick count in the top left under the Dora indicators
  • If the dealer wins, they get an extra 50% points than the hand would normally get
  • If you win via Tsumo, all players pay you points with the dealer paying a larger share
  • If you win via Ron, the player that discarded your winning tile pays all the points
  • See Bonus Han for additional Han options
• Draws
  • If no one wins after the last tile is discarded, players in Tenpai split 3000 points from players not in Tenpai (Noten). You do not need a Yaku to be in Tenpai
  • If all players Riichi, the hand is a draw
  • If all players discard the same wind on their first discard, the hand is a draw
  • If a player starts with nine different terminal and honor tiles, they may choose to reveal their hand and force a draw
  • Any Riichi antes stay in the pot until someone wins a hand
  • The dealer stick count will always increase for a draw
• Furiten
  • If one of your wait tiles has been discarded by you, you are not allowed to call Ron to win. You'll have to either Tsumo or change the tiles you're waiting to win
  • If you do not claim Ron on one of your opponents (because you don't want to steal their points or are going for a more valuable wait), you have to wait until after your next discard before you can claim Ron again. If you are in Riichi and do this, you can never claim Ron and have to wait for Tsumo
• End of game
  • The game ends after all four players have been dealer at least once (East game, one round of dealers) or twice (South game, two rounds of dealers)
  • The dealer (East seat) does not change if the dealer wins the hand, is in Tenpai when the wall runs out of tiles, or if there is a draw
  • If after the last dealer round no players have 30000 points, play continues until someone does

See General Strategies for some beginner advice