Perhaps a bit unusual but this is thread dedicated to the numerous works of Nobuyuki Fukumoto. I've been meaning to make this thread for a long time but I've struggled to work out how to explain his series.

Let's have a look see;

Ten (1989-2002)
In his first series, following the exploits of Ten, FKMT starts it off as a fairly light hearted slice of life mixed with games of Mah-jong. Ten helps local mah-jong parlours deal with the Yakuza in games of high stakes mah-jong. We see this through the eyes of Hiroyuki, a recent college graduate who becomes interested in Ten and what he's up to. Soon the slice of life comedy elements are quietly removed and the series lays into it's main arc. Ten has now become a prominent figure in underground Mah-jong and leads the defence when Players from East Japan want too change the balance of power, among other things.
Ten's team includes the outclassed Hiroyuki and the gambling genius Akagi. They're set against the leader of the East and feared Yakuza boss Haradra and former mah-jong demon, Soga. After that things get... depressing.
The art is characteristically ugly but not without charm, the tension is high and though matches can last whole volumes it feels well paced once you get past the rather bad opening.
Full scans can be found here.

A spinoff from Ten is;
Akagi
Focusing on fan favourite, Akagi Shigeru's early life it's more of the same but with a different flavour. Where Ten is about how the players can make logical assumptions about what their rivals are up to (with the occasional lucky guesses) Akagi is about doing the unexpected, getting into his opponents head and messing with them. He takes the stakes as high as possible, frequently putting not just himself but his allies in danger of financial ruin and even putting his life on the line. The series has yet to end but what has been done so far has been made into an anime series which is wel worth a look if you can deal with lots of jargon.

Don't worry if you know nothing about mah-jong. While the series makes no real effort to explain things it's pretty easy to figure out when something important is kicking off.
Scnas!

Ultimate survivor: Kaiji
Kaiji is a young layabout, suffering at the hands of a recession, unable to find work. One day he finds out his friend has forged his signature and gotten them both into a very steep debt with the wrong people. He's tricked into taking part in a method to pay off his debts, a gambling event on a lovely cruise ship. Things don't go well.
Where Akagi was about the protagonist inflicting mind games on others, Kaiji is on the receiving end. The games, while very simple, put a lot of pressure on the player. Also, where Akagi is a cold hearted monster who doesn't think about losing, Kaiji is much more human, clearly terrified of losing and using this terror to help take greater risks.
This series is still running its course but the first two major arcs have been animated by the same team who did Akagi. Even if Akagi wasn't for you you should still check this out.
Scans!

Buraiden Gai
I'm not actually to familiar with this series. What little I do know is that it concerns 13 year old outcast Gai and the sinister Human Institute which doesn't seem overly fond of young people. Scans can be found here.

Gambling Emperor Zero
A personal favourite of mine, GEZ follows Zero, a genius young boy who, after being caught pulling a Robin Hood against some Yakuza is invited to a Gambling contest to determine who will represent a crazy old man in an even bigger gambling event with stakes so high it would make Bill Gates dizzy. Unfortunately the contest runner cares litle for the players and many of the games are rather harmful. The games are mostly logic puzzles with the main pressure being having to deal with the other players panicking for their lives. It's pretty damn awesome if you ask me but is also on Hiatus after a very literal cliffhanger.
Scans!

Now, there are other series by Mr. FKMT, such as fan favourite "Kurosawa: The worlds strongest man" so I encourage you to go seek them out. Also worth finding is One Outs, a series in the similar vein to many of these series but about baseball.
Ones outs, Akagi and Kaiji are generally recommended as some kind of holy trinity of gambling series and I'm happy to go along with this.


Geze that sure was confusing! Can I sum it up nice and quick?
Go read Kaiji and Ten. If you like those then check out the other series.