Sleeping Dogs: Definitive Edition

While this can be earned at any of the cockfighting arenas, your best bet is to save up a few hundred thousand, at least $300k, then go to the one at the Kennedy Town docks, north of the martial arts club. Save before you place any bets!

The minimum stakes here are $50k, but bump it up to $100k, as you're looking to kill three birds with one stone. The fights are random, there's no concrete evidence supporting a particular strategy. You want more than the maximum bet if/when you lose the first fight, in order to save time getting back to the docks.

Should you end up on a losing streak, reload your save and try again. As soon as you end up with more money than you came in with, save your game and continue. This will help preserve your progress on the Gambler stat award, as you need to make $1m, or effectively win ten times in a row, and losses will cut into that progress.

As soon as you win the extra $100k, you'll earn this achievement as well as one other.

***First I'd like to note that this guide is not 100% accurate and it is based on loose observation and taking notes while trying to get the "Gambler" challenge done. The bird can sometimes be beaten even with odds on your side for example when your bird starts running outside circle you most likelly going to lose that round. There isn't definitive guide to win 100% of cockfights, it's pure RNG. Might not work with Definitive Edition ***

Breeds:
There are 4 breeds of birds: Croad Langshan, Jersey Giant, Rhode Island Leghorn and Buckeye Brahma. Every breed represent different class in game which gives every bird unique stats. Using this "strategy" i earned myself 2 mil HK $.

Croad Langshan is Striker;
Jersey Giant is Grappler;
Rhode Island Leghorn is Brawler;
Buckeye Brahma is Armed;

Strikers beat grapplers but loses to brawlers or armed;
Grapplers beat armed and brawlers but lose to strikers;
Brawlers beat strikers but lose to grapplers;
Armed beat brawlers and strikers but lose to grapplers;

Strategy

So, considering given theory the strategy looks like this:

Croad Langshan (striker) will beat Jersey Giant (grappler);
R.I. Leghorn (brawler) will beat Croad Langshan (striker);
Buckeye Brahma (armed) will beat Croad Langshan (striker);
Buckeye Brahma (armed) will beat R.I. Leghorn (brawler);
Jersey Giant (grappler) will beat Buckeye Brahma (armed);
Jersey Giant (grappler) will beat R.I. Longhorn (brawler);

Hope this guide will help you to build a fortune.