#111 Building an AI to Play Video Games with Python

Gene Da Rocha - Jun 4 - - Dev Community

In this article, we will see how Python can make an AI. This AI will learn to play video games. We will mainly talk about Reinforcement Learning and Deep Reinforcement Learning with the game Snake. Also, we will show how to use Keras in TensorFlow and PyTorch to make the AI learn and get better at the game.

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Python Game AI

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This method uses a game environment , like the Snake game, for the AI. The AI learns about its situation and then decides what to do. The game gives good or bad points based on what the AI does. This helps the AI learn to make choices that get it more good points, like eating apples and not hitting walls.

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Key Takeaways:

  • Python is great for making AI that plays video games.

  • Reinforcement Learning and Deep Reinforcement Learning are good for teaching AIs.

  • We can use the Snake game to show how these AI methods work.

  • Keras, TensorFlow, and PyTorch are tools to make Deep Reinforcement Learning models.

  • Using these tools, we can make AIs that get very good at video games.

Understanding Artificial Intelligence and Gaming

Artificial Intelligence and Artificial behaviour in games are different. The goal in gaming is not to make AI agents beat players. It's about making games fun and interesting. Games help in training virtual agents for various real-world tasks.

For instance, Google DeepMind's AlphaGo made history by defeating the top Go player. This showed how powerful AI can be in mastering complex games. But our focus here is on another AI use in gaming , teaching an AI to play Snake using Reinforcement Learning.

Reinforcement Learning helps AI agents learn from their environment. The AI interacts with the game, getting rewards for good moves or penalties for bad ones. It learns to make moves that lead to rewards, like eating the apple in Snake, and avoid bad moves, like hitting walls.

By using Reinforcement Learning, game developers can make AI that adapts to play better. These AI agents can offer tough, but fair, challenges to players. They don't need to use strategies that are too hard to predict, causing frustration.

"The goal of gaming AI is not to replace human players, but to enhance the gaming experience and create new opportunities for interactive and immersive gameplay."

As tech improves and gaming gets more popular, we see more AI in games. From realistic NPCs to smart enemies, AI has changed games a lot. It makes games deeper and more fun by adding human-like behaviours and surprises.

In the next part, we'll look at Reinforcement Learning basics. We'll see how it trains an AI to play Snake. We'll look at the training steps and ways to make the AI play better. Let's start this great journey into AI gaming!

Stay tuned for the next section: The Basics of Reinforcement Learning!

The Basics of Reinforcement Learning

Reinforcement Learning is like a toolbox full of ways to make decisions, especially in games. It sees games as Markov Decision Processes (MDPs). These MDPs have states, actions, rewards, and how things move between them.

We will look mainly at Deep Q-Learning here. It's a kind of Reinforcement Learning. Deep Q-Learning uses a Q-table to match states, actions, and the likely rewards. This method is better than regular Machine Learning because it uses deep neural networks.

The Game and Its Components

We will look into the game of Snake and how it works with Deep Reinforcement Learning. Snake is a classic game made with Python. It uses the Pygame library. This makes a fun place for the AI agent to learn.

The Deep Reinforcement Learning has two main parts: the game itself and the Snake. The game is the world the Snake lives in. It tells the Snake where it is, how fast it's moving, and where the food is. The Snake uses this to make choices and moves to win points.

Whenever the Snake does something good, like eating food, it wins points. But if it hits a wall or itself, it loses points. This helps the Snake figure out what to do and what not to do.

So, the Snake plays and learns from its wins and mistakes. It gets better over time, getting smarter about how to eat and not get hurt.

Now, let's dig deeper into the game and how it all works together.

The Training Process

The AI agent starts learning the game from scratch. It does this by taking random actions. This helps it learn what works and what doesn't.

The agent uses the Deep Q-learning algorithm to get better. It updates its Q-values in the Q-table. This helps it learn from its past actions and make smarter decisions.

The agent remembers everything it does in the game. It notes the starting state, the action taken, and the results. This helps the Deep Neural Network to learn and improve the agent's moves.

The article also talks about Bayesian Optimization. It helps make the Artificial Neural Network better. This leads to the agent playing the game more effectively.

The Training Process Overview

Here's a step-by-step of how the AI agent learns to play:

  1. Start by putting random values in the Q-table.

  2. Let the AI agent take random actions in the game.

  3. See the state of the game after the actions.

  4. Choose what to do next based on the current state and the Q-table.

  5. Look at the results of the action taken.

  6. Change the Q-value depending on what was learned from the last action.

  7. Do steps 3 to 6 over and over until a goal is reached.

  8. Teach the Deep Neural Network using all this information.

  9. Make the Artificial Neural Network better through Bayesian Optimization.

By repeating these steps, the AI agent gets better at playing. It learns and grows with each action, becoming skilled at the game.

"The training process is key. It's where the AI agent learns to play better by trying new things. This makes it perform better each time it plays."

The State Representation

In the Snake game, the state has 11 pieces of data. These data show where the Snake is. They help the computer player know what moves to make.

These 11 parts of data are set up like this:

  1. Immediate Dangers: Some parts show if there's danger nearby. The game looks at these to stay safe.

  2. Current Direction: The Snake can move up, down, left, or right. This data helps it figure out what to do next.

  3. Location of the Food: Other parts tell where the food is. They say if it's above, below, left, or right of the Snake. This helps the Snake find the food.

The state data goes to a Deep Neural Network. This lets the game plan its moves wisely. It looks at the Snake's place, dangers, and food spot to do well.

Here is how the state data could be shown:

Variable Value Immediate Danger - Right True Immediate Danger - Left False Immediate Danger - Straight False Current Direction Up Food Location - Above True Food Location - Below False Food Location - Left False Food Location - Right False

Note: The above example is for illustrative purposes. It might not match a game situation exactly.

The AI uses this state data to play smartly. It helps the Snake find food and avoid trouble. This method, with Deep Neural Networks, guides the AI in the Snake game.

The Loss Function and Reward System

This AI uses a Neural Network to make choices. It looks at what's happening to get the best score. The loss function checks how close it gets to the right answer. It wants to be as correct as possible.

In the game Snake , good points are given for eating the apple. But, if the Snake hits the walls or itself, it loses points.

It gets even better. The Snake can also earn points for staying alive. But, if not done right, this can cause problems.

Finding the right loss function is important. It helps the AI learn from mistakes. This way, it can do better over time.

The game rewards good moves and punishes bad ones. When the Snake eats the apple, it earns points. But it loses points by running into walls or itself.

If the Snake survives, it earns more points. Yet, if not balanced, it might not try to eat the apple. Balancing this is key. It makes sure the Snake plays the game right.

Setting up the right rewards is tricky. Too much focus on just surviving can make the Snake forget to eat. Finding this balance is crucial.

Reward Description +10 Reward for successfully eating the apple -10 Punishment for hitting the walls or the Snake's body Variable Possible positive reward for surviving each step without dying

The Deep Neural Network Architecture

The AI agent in this game uses a Deep Neural Network (DNN). It has three layers with 120 neurons each. This setup helps the agent learn quickly and do better in the game.

The DNN has hidden layers for doing complex math. This lets the agent see detailed patterns and behaviours in the game. More hidden layers mean the DNN can understand the game better and make smarter choices.

The learning rate is very important. It decides how fast the agent learns from new things. In the game, the learning rate starts at 0.0005 and gets smaller to 0.000005. This slowdown helps the agent get good at the game over time.

The Role of Hidden Layers

The DNN's hidden layers turn the game data into something it can process. They find key features and patterns. This helps the agent see the game world more clearly.

Adding more hidden layers helps the DNN see the game world in even more detail. Then, the agent can make better choices for winning. Many hidden layers also make the DNN smarter at handling different game situations.

Exploring Other Search Algorithms

This article focuses on Deep Reinforcement Learning, but we'll talk about more. Other search algorithms like Minimax, Alpha-Beta Pruning , and Negamax are used in-game strategies. These algorithms look for the best moves in a game. They use special rules and ways to make searching faster and better.

"The essence of strategy is choosing what not to do."

  • Michael E. Porter

Game AI uses search algorithms to make smart choices. There are three main ones we'll talk about here.

Minimax Algorithm

The Minimax Algorithm helps in games where two players play. It tries to lower the worst possible loss. It checks all possible moves to decide the best one to make.

This works well in games like chess and tic-tac-toe. These games show all the information, not hiding anything.

Alpha-Beta Pruning

Alpha-Beta Pruning makes Minimax search faster. It doesn't look at moves that won't matter. This makes the search process much quicker.

Negamax Algorithm

In the Negamax Algorithm , the game looks simpler. It treats every turn like it is the best possible turn. This makes the thinking process easier to write down.

These algorithms are just a start to making AI smart in games. Game makers use many of these together to make fun and challenging games.

Algorithm Pros Cons Minimax Algorithm Optimal decision-making in two-player games with perfect information Computationally expensive for games with large search spaces Alpha-Beta Pruning Significantly reduces the number of nodes explored, improving performance Requires careful ordering of move evaluation to maximize pruning efficiency Negamax Algorithm Simplifies implementation by removing the need for separate evaluations for each player May lead to redundant evaluations of the same game state

Conclusion

We learned about building an AI agent with Python. It plays games using Reinforcement Learning.

This lets developers make smart game players. These players learn and get better over time.

First, we talked about what Reinforcement Learning is. Then, it is used in games.

Next, we looked at the game Snake. We discussed how the AI learns from it.

We also saw how the AI player gets better. It learns how to get more points in Snake.

We talked about the AI's brain, called a Deep Neural Network. Other ways to make good game moves were mentioned, too.

Python AI in games is very cool. It helps make game characters smart.

With AI, games can be more fun and interesting. There's a lot more to discover in the future of game AI.

FAQ

What is the goal of creating AI agents in gaming?

The goal is to make games fun, not to beat players. Games help teach AI to be better at many things.

What is Reinforcement Learning?

It's about learning from playing and getting rewards in games. Reinforcement Learning treats games like puzzles to solve.

What is the Deep Q-learning algorithm?

It's a smart way for AI to learn from games. Deep Q-learning uses a table to learn which actions are best.

What is the game Snake?

Snake is a simple game made with Pygame in Python. It's used to show how AI can learn to play well.

How does the training process work?

At first, the AI knows nothing and plays randomly. It learns what's good and bad by trying and getting rewards. Later, these lessons help it play better.

How is the state represented in the game Snake?

The game's state is shown with 11 true or false facts. These show where dangers are and where food is.

What is the role of the Deep Neural Network in the AI agent?

The network helps the AI choose actions in the game. It aims to pick the best move based on game situations.

What other search algorithms are commonly used in game strategy?

Search methods like Minimax and Alpha-Beta help plan moves. They try to find the best path forward in games.

What have we covered in this article?

We learned about making AI to play games. We talked about playing Snake to show how this works. And we looked at tools and methods for teaching AI.

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