6 Block Theory

5 Block Theory is standard in Western riichi play. So what is 6 Block Theory?

Let’s look at the hand from the 5 Block Theory article.

That can be divided into 6 blocks. Rather than looking to reduce a block as we move to five groups, we look to retain one so instead choose to throw 3p or 4p from this shape and keep the less strong 12s shape.

What are the benefits of the 6 Block strategy? The main benefit is that you can act with more flexibility to developments on the rest of the board whereas 5 Block theory can lock you into areas of suits. If a critical tile is kanned or ponned, effectively blocking you progressing your hand, it can be very difficult to pivot and you may not have time to rebuild in another area.

The disadvantage of the 6 Block strategy is your 1-away (iishanten) shape can be weaker compared to a hand crafted with 5 Block strategy. You’ll still be in a state where you’re shedding an excess block if you’ve applied 6 Block theory.

You can almost think about 6 Block theory is simply delaying application of the 5 Block theory. Any mahjong player can tell you that delay comes with risks…

Consider you’d applied the 6 block theory and you draw a 6m… Your path to tempai from this shape is significantly weaker than if you’d retained the 4p.

The above assumes you next discard the 12s shape as is conventional. Compare to a regular 5 Block application….

That may be enough to put you off a 6-Block application.

So when does 6 Blocks come in handy?

1) You want to be able to pivot to defence, 6 Blocks can give you greater spread and the flexibility to defend without choosing to retain an explicit safe tile.

2) The impact of a dora. For example, if that 4p were the dora, you’re not going to throw it even if you get a triplet of 3p. Keeping an excess 3p could become increasingly dangerous as the hand progresses and cutting it now could be advantageous.

3) You have an eye on a yaku but you’re not entirely committed. I’ve found it particularly useful when I’d like to build sanshoku value in but my hand is not well enough progressed in that direction.

In summary, 6 Block theory is not something I would recommend until one has reached an intermediate level of mahjong. It sacrifices speed and your 1-away (iishanten) shape for the sake of other strategic elements that require good judgement on the situation and your winning criteria. That sort of judgement is best developed through experience so keep playing!

Let me know if you’ve tried this out and whether you have any other comments you think I should be considering in the article!