My understanding of Mahjong is that you need four players. Is that right? Or is it possible to play with 2 or 3? If so, can anyone assist with a link to the rules.
These rules have 2 and 3 person variant rules.
So yes you can play with 2 or 3 people as well.
Here's the relevant rule changes:
Two-Player Mah Jong
This is good practice for beginners although not quite such a good game as the more typical version with 4 players. One player plays East, the other West. The preliminaries are conducted in the same way as for the 4 player game, 4 walls are built and the game starts with East's discard. The game continues as with the standard game but with the following differences:
No chows are allowed and therefore before either player can go Mah Jong, the player must gather four doubles or be entitled to the limit or half-limit score. When scoring, East Wind neither pays nor receives double. When scoring, the player going Mah Jong has a lower score than the player's opponent, the player with the Mah Jong receives the normal total score plus the difference between the scores.
Three-Player Mah Jong
There are two main ways to play three-player Mah Jong. One common way to play is with four walls but to have the North wind position as a 'dummy'. The alternative is to play with 3 walls in a triangle. The 'dummy' method results in a satisfactory game but there are a number of special rules that are required and Masters Traditional Games believes that the triangular game for three players is simpler and more elegant and so that is our recommendation.
In South East Asia, Triangular Mah Jong is so popular that there are companies who make special triangular Mah Jong tables.
Triangular Mah Jong for 3 players eliminates the North position completely and the 4 North wind tiles are removed from the set before starting so that a set of 132 tiles are used.
The walls therefore consist of 22 stacks (44 tiles) in a triangle shape and there are 3 hands in each round and 3 or 4 rounds as agreed. Other than that, the game is played in the same way as for 4 player Mah Jong.
If flowers and seasons are included, one season and one flower is removed, usually Winter and Bamboo tiles so that 138 tiles are used and each wall consists of 23 stacks (46 tiles).
We have a mahjong set and regularly play with only three people but using the same rules as the four-player game. The only difference is that it is often slightly easier for someone to win with three players. That said, we still goulash every so often. The two player game is also possible using different rules, usually with making all pairs in a hand, however I find this method a bit boring so we still play normal rules with two players. That way someone always wins a hand, just more quickly.
One piece of advice I have is to treat the game as fun! I have met many people who are so serious about what is or isnt 'allowed' in playing mahjong that it can be a bit off putting. Why not try the usual play with fewer people--it's just as much fun even if you aren't changing the rules to suit fewer than four...