Not everyone plays the same way, and while standards appear and evolve over time, take note of variations in the way people play Reach. Here’s a list of a number of things you’ll commonly see as variations within Reach Mahjong today. When playing in a new parlor or with a new group of people, it’s best to look into how each of these things are done.
Common Variations
Open / Closed Tanyao (kuitan ari, kuitan nashi) – Is Tanyao an open Yaku, or must you be closed to get it.
Backdoor Waits / No Backdoor waits (atozuke ari, atozuke nashi) – Are you allowed to Ron if there are waits in your hand that you cannot win on. For example, 
if you only have Tanyao, or 
if you are North in East 1.
These first two are important, as they are often announced together, and are the most varied. “ari ari” means “tanyao is open and backdoor waits are allowed”, “nashi nashi” means “tanyao is closed and backdoor waits are not allowed”.
Kandora flip timing – For closed kans, the new dora flip often occurs right away. but for called / upgraded kans, when does it flip? Right away? After discard? And if it is a Rinshan win, does the winner get the new dora as well?
Ryanhan Shibari (2 yaku minimum at 5 repeat deals) – Are two yaku required if there are 5 or more repeat deal markers out?
Head Bump / Multiple Ron – if someone deals into multiple players, do they pay all of them, or just the first in the upcoming draw order? If there are multiple Reach sticks on the table, how are they given to the multiple winners?
Exhaustive Draws – what ends a hand prematurely? All players discarding the same wind on the first go-around? Four Reaches? Four kans (by different people)? Kyuushuu Kyuuhai (a player deciding to end the hand by having nine or more different terminals on their first draw)?
Furiten Clearing – If a player is in temporary furiten by passing on a win, do other player’s calls clear it, or only the furiten player’s draw?
Oka (ante) – This is the number of points set aside at the beginning of the game to be claimed by first place at the end. Commonly, this is 5,000 points per player (as in, they “start” at 30,000 points, but all begin East 1 at 25,000).
Uma (placement bonus) – post-game payments determined by placement. This can either be in a 1st-through-4th listing (example: +30/+10/-10/-30, which means “1st gets 30,000 points, 2nd gets 10,000, 3rd loses 10,000 points, 4th loses 30,000”) or in a single listing (example: “10” means “each player pays 10,000 to each player above them” – note that this is functionally identical to +30/+10/-10/-30)
Optional Rules
Red Tiles (often red fives) – these are treated as dora: han that only count if the hand is won via other yaku. One red five in each suit is most common, followed by no reds at all, followed by four red fives (one of each and two in pin). San Group (a large parlor chain) uses two “red threes”, in pin.
4 and 30 Mangan (“kiriage mangan”) – this means that a 4 and 30 hand is treated as a 4 and 40 hand (mangan). So, instead of non-dealer 7700, you pay 8k. instead of dealer 11600, you pay 12k. This is extremely common.
Chips – Chips are an additional payment method. Chips are given a value (for example, 100y or 500y), separate from the actual points of the game. Winning with certain han (most often ippatsu, red dora, and uradora) also won you chips. For example, reach tanyao dora 1 reddora 1 uradora 1 would be worth 2 chips. These chips are paid directly from player to player, along with the points for the hand (the chips do not affect the points won or lost, nor do they count as points in any way). In case of a Ron, the chip count is paid by the dealing-in player (2 chip hand = 2 chips paid). In case of a tsumo, however, all players pay the full amount of chips (2 chip hand = 2 chips paid by each, for a total of 6 chips obtained). Often, games with Chips have two additional chip-gaining rules: Yakuman are 10 chips (or 5 from each player) and Allstar hands (parlors with three red dora, and all three red dora are in the hand) are also 10 chips (or 5 from each player). These are instead of the chips the hand is worth.
Gold Dragon – one of the White Dragons will have a mark on it (usually an inset gem – this tile still counts as a White Dragon as well). If this tile is drawn by someone who reached as the first tile they’ve drawn after reaching, it counts as the tile of their choice (wild).
For example, A player reaching with 
and drawing a Gold Dragon could take it as 
(instead of or ) and would get Reach Ippatsu Tsumo Pinfu Itsu.