What is the Poker Game Tree & Why Does It Matter?

Learning poker is a gradual process.

You start by learning about your hand strength and play poker without factoring in much else. Gradually, you start to consider more factors like board texture and ranges. But as you become a more advanced player, you start to look at the game differently.

Sophisticated, high-level players take a macroscopic, birds-eye view of the entire game. In other words, they familiarize themselves with the entire “game tree” of poker.

If you’re unfamiliar with the term game tree, don’t worry. This article is designed to bridge that knowledge gap so you can start viewing poker like the world’s best players.

Let’s dive in.

This article is marked as advanced. If you’d prefer easier reading, check out our introductory articles here or intermediate articles here.

What is a Game Tree?

Poker is a sequential game (like chess or tic-tac-toe) as opposed to a simultaneous game (like rock-paper-scissors). This means that only one player acts at a time.

An inherent attribute of sequential games is that players have some knowledge about earlier actions, with the exception of the first move of the game. This is the root of positional advantage in all sequential games — if you act last, you have an advantage in the form of extra information.

Sequential games can be represented in what is called extensive-form, also known as a game tree. A game tree is a graph with nodes that represent positions in a game and lines that represent potential actions. For example, here’s a piece of the game tree for tic-tac-toe:

The poker game tree is an abstract concept that high-level poker players have adopted to better understand the best ways to develop strategies. This understanding allows them to capture more expected value (EV) than their opponents.

What Does the Game Tree Look Like?

The game tree looks something like this (bear with me, I’ll explain what you’re looking at):

Each decision point, also called a node, gives birth to new branches (each representing an option, such as bet or check). These branches births new nodes, and so on. If you look at it upside down, it looks like a tree, hence the name.

The tree starts from the first preflop decision, at which point a player has 3 possible decisions: fold, call or raise. After a raise, for example, the next player can fold, call or re-raise. For each of that player’s decisions, the next player can fold, call or re-raise, and so on.

After all the preflop actions are done, the flop comes and each player can fold, check, call or bet/raise.

You can see how the deeper you go into the tree (preflop -> flop -> turn -> river), the possibilities multiply exponentially, having all started from a simple node of 1 player’s 3 options. When you add in the possibility of multiple bet sizes, then the tree becomes exponentially bigger once more.

Why Does the Poker Game Tree Matter?

The knowledge of the game tree, on its own, doesn’t bring many practical benefits. Why is it important, then?

When the game tree was coupled with the advancements made in computing power and software development, the creation of poker solvers was possible.

The game tree provided a logical way of organizing the game of poker, which software (like PioSolver) can understand. The software can use the game tree to test competing strategies against each other until it reaches what is known as the Nash equilibrium.

The Nash equilibrium is a set of strategies that neither player can deviate from to increase their EV. In other words, if one player plays at equilibrium, the best that the opposing player can do is play his part of the equilibrium strategy. Any other strategy will result in a loss of EV.

Editor’s note: You may have heard the Nash equilibrium poker strategy referred to by its more popular and often misused label, game theory optimal (GTO).

That being said, if one player is not playing the equilibrium strategy, then the opponent can successfully deviate from his part of the equilibrium strategy to increase his expected value. This is always the case in poker because no poker player is capable of implementing a true equilibrium strategy in-game — though the world’s best players do a great job trying.

Related reading: 4 GTO Myths That Way Too Many Players Believe.

Practical Implications

Considering how your strategy looks throughout the game tree allows you to eliminate exploitable weaknesses and bolster your overall approach.

Think about this:

What would happen if you made all of your poker decisions based only on your specific hand and the board with no considerations for later parts of the game tree?

The answer: you would end up with very exploitable leaks in your strategy.

For example, suppose you continuation bet (c-bet) on the flop with 100% of your flush draws and straight draws while checking back some medium-strength hands. If you built your flop c-betting range in this way, your check-back range would completely lack flushes and straights when they complete.

If a knowledgeable opponent catches on, she can start using very big bet sizes to exploit your flush-less, straight-less range. She could do this with thinner value bets while vastly increasing her bluffing frequency, rendering her a much higher EV at your expense.

Using this logical representation of the game, early adopters of the game tree have found it to be an amazing tool to spot leaks in their opponent’s frequencies at different nodes. Once the leaks are identified, it’s a simple matter of creating counter-strategies to exploit them.

Conclusion

Can you crush lower stakes without having heard about the game tree? Absolutely!

Can you crush mid-high stakes online without implementing strategies that are built on this framework? Absolutely not!

I hope this article opened your mind to a whole new view of the game of poker. As usual, if you have any questions or feedback please let me know in the comment section down below.

Want to take a fun quiz now? Try your hand at our $2/$5 live poker quiz!

Until next time, good luck, grinders!