Guide - Starting Mahjong

This guide is meant to get a new player to rough Mahjong competency. When learning a new skill, progress isn't a straight line. There's a sharp spike at the start that later levels out. In this article, we'll climb the spike, and then Riichi Book 1 and other resources will cover the rest.

Analysis - The Last Two Discards Of A Suit

In this post, we'll look at how a player's riichi tile, combined with the previous tile of that suit they discarded, affects the frequency of their ending waits. What does it mean when they cut a pair? Does it matter if they cut their kanchan starting from the inside or the outside? Let's find out.

Analysis - Ura Suji and Matagi Suji

I wasn't really happy with my previous analyses that included ura suji or matagi suji. The data was kind of noisy. So, this time, I'll be narrowing the search to make it clearer.

Analysis - Suji Effectiveness Based On Riichi Tile

Suji is safer when you have reason to believe your opponent has a good wait. If they have a single wait or a shanpon shape, then suji won't apply to them. There are many tells that indicate that a player might have a good wait, but here, we'll look at a very simple one: the tile they called riichi with.

Analysis - Yaku Rates by Hand Type

People commonly wonder how rare certain yaku are. Something I've been curious about is how common certain yaku are in open hands. So, let's look at the yaku distribution for all hands, riichi hands, dama (closed tenpai without riichi) hands, and open hands.

Training Tool - Akochan Reviewer

Akochan Reviewer is a tool that leverages the akochan mahjong AI to analyze replays. It looks at rank point EV, rather than round/hand EV, and covers efficiency, calling, riichi decisions, and push/pull. It's designed for Tenhou replays, but can work with rounds from Mahjong Soul and anything else if you're willing to put in some work.

Analysis - Ura Rates by Unique Tiles in Hand

I've seen enough people asking about the chance of getting ura dora that I decided to check the Houou replays to see the chance.

Guide/Analysis - Defense Techniques: Kabe and One-Chance

Another common defense technique is kabe, or in English, wall or blockade. When you can see four of a tile, the player can't have that ryanmen, and sometimes it also removes the chance of kanchan. There's also one-chance, when you can see three of a tile. Let's check out how safe they are.

Guide - Defense Techniques: Aida Yon Ken

In this post, we'll talk about an uncommon defense technique called Aida Yon Ken, which refers to four-tile gaps in an opponent's discards, and check the Houou replays to see how much weight it holds.

Analysis - Wait Win Rates by Row

Previously, we looked at the wait win rate of every riichi hand. This time, we'll look at the wait win rate of every riichi hand, separated by row.

Analysis - Sotogawa Effectiveness by Turn and Tile

We've talked about sotogawa before, but the exact effectiveness and extent wasn't really clear. Does a 4 discard create sotogawa tiles? How late can a tile come out before not counting for sotogawa? I dug into the Houou replays hoping to answer these questions.

Analysis - Wait Win Rates in Riichi Hands

I ran through 1.2 million Houou replays and checked the wait of every riichi hand, as well as whether it won or was furiten. Let's see the results!

Analysis - Tile Deal-in Rates by Live Suji

Suji counting is a good strategy for estimating the danger inherent in cutting a non-suji tile. But, how much of an effect does each dead suji have? Let's check out some data from the Houou replays.

Interesting Replays

Doing analysis on the Houou replays sometimes results in some strange discoveries. I'll add to this list whenever I find one.

Guide - Defense Techniques: Kuinobashi

Kuinobashi is a method for identifying a dangerous wait in an open opponent's hand. We'll go over the technique, as well as look at some data from the Houou replays to see if it has statistical merit.

Analysis - Tile Win Rates in Riichi Hands

In this post we'll look at how often players win on each tile, and how that changes based on their discards, early discards, riichi tile, and the dora indicator.

Guide - Defense Techiques: Sotogawa and Matagi Suji

In this post, we'll look at sotogawa tiles and matagi suji, including checking Houou replays for some related statistics to back up the theory.

Guide - Extremely Minor Advantages: Lone Honours

When deciding between which lone guest wind or which lone dragon to discard, the choice may seem arbitrary, but there are tiny advantages you can gain based on your decisions. Let's take a look.

Analysis - Kokushi Success Rates

In this post, we'll look at how Houou players deal with different kokushi starts. Do they go for kokushi, or abort? Do they try and give up? If they go for it, how often do they get it? If they don't go for it, how often do they win? We'll look at these for the three main game modes, 4P Hanchan, 3P Hanchan, and 4P Tonpu.

Analysis - The Average Houou Player

For the first analysis, we looked at the average Houou game. But, what about the average Houou player? The average call, riichi, win, and deal-in rates? Tenhou's ranking page uses stats from all rooms in its averages, so let's see what the averages are in only Houou games.

Training Tool - Mattari Mahjong

Mattari Mahjong is a single-player Windows application with some fairly tough bots. But, it has a lot more to offer than just that, including defense and push/pull evaluations. It's also very fast, so it's perfect for slipping a game in here and there. But, of course, it's in Japanese, so here's a guide.

Analysis - Second Dora Dragon

This is a quick followup to one of my previous analyses, Lone Dora Dragons. In that, we looked at the danger of discarding a lone dora dragon from your hand. In this, we'll look at the danger of discarding the second.