A Simple Battlesnake Written in Dart with Shelf

This is a basic implementation of the Battlesnake API. It's a great starting point for anyone wanting to program their first Battlesnake using Dart. It comes ready to use with Repl.it and provides instructions below for getting started. Once compiled, it can also be deployed to Heroku, or any other cloud provider you'd like.

This project is copied and modified from the Kian Gorgichuk's TypeScript Starter Project, of which was copied and modified from Battlesnake's offical JavaScript Starter Project project.

All typing documentation was copied from the Kian's TypeScript Starter Project, which was copied from the offical Battlesnake docs.

Technologies

• Dart
• Shelf
• Shelf-Router

Prerequisites

• Battlesnake Account
• Repl.it Account
• GitHub Account (Optional)

Running Your Battlesnake on Repl.it

1. Login to your Repl.it account.

2. Click the 'Run on Repl.it' button above, or visit the following URL: https://repl.it/github/hotdang-ca/starter-snake-dart-shelf

3. You should see your Repl being initialized - this might take a few moments to complete.

4. Once your Repl is ready to run, click Run ▶️ at the top of the screen.

   Note: you may have to show the Shell and run:

   dart pub get
   

5. You should see Dart Shelf (and any other dependencies) being installed. Once installation is complete, your Battlesnake server will start and you should see the following:

```
Dart Shelf Battlesnake Server listening at port 8080
```

5. Above the terminal window you'll see the live output from your Battlesnake server, including its URL. That URL will be the URL used to create your Battlesnake in the next step. If you visit that URL in your browser, you should see text similar to this:

   {"apiversion": "1", "author": "", "color": "#888888", "head": "default", "tail": "default"}
   

This means your Battlesnake is running correctly on Repl.it.

At this point your Battlesnake is live and ready to enter games!

Registering Your Battlesnake and Creating Your First Game

1. Sign in to play.battlesnake.com.

2. Go here to create a new Battlesnake. Give it a meaningful name and complete the form using the URL for your Repl from above.

3. Once your Battlesnake has been saved you can create a new game and add your Battlesnake to it. Type your Battlesnake's name into the search field and click "Add" to add it to the game. Then click "Create Game" to start the game.

4. You should see a brand new Battlesnake game with your Battlesnake in it! Yay! Press "Play" to start the game and watch how your Battlesnake behaves. By default your Battlesnake should move randomly around the board.

5. Optionally, watch your Repl logs while the game is running to see your Battlesnake receiving API calls and responding with its moves.

Repeat steps 3 and 4 every time you want to see how your Battlesnake behaves. It's common for Battlesnake developers to repeat these steps often as they make their Battlesnake smarter. You can also use the "Create Rematch" button to quickly start a new game using the same Battlesnakes and configuration.

At this point you should have a registered Battlesnake and be able to create games!

Customizing Your Battlesnake

Now you're ready to start customizing your Battlesnake's appearance and behavior.

Changing Appearance

Locate the _rootHandler function inside hello_battlesnake.dart. You should see a line that looks like this:

final mainResponse = MainResponse(
    apiversion: '1',
    author: '',
    color: '#888888',
    head: 'default',
    tail: 'default',
);

This constructor is called by the game engine periodically to make sure your Battlesnake is healthy, responding correctly, and to determine how your Battlesnake will appear on the game board. See Battlesnake Personalization for how to customize your Battlesnake's appearance using these values.

Whenever you update these values, go to the page for your Battlesnake and select 'Refresh Metadata' from the option menu. This will update your Battlesnake to use your latest configuration and those changes should be reflected in the UI as well as any new games created.

Changing Behavior

On every turn of each game your Battlesnake receives information about the game board and must decide its next move.

Locate the _moveHandler function inside hello_battlesnake.dart. Possible moves are 'up', 'down', 'left', or 'right'. To start, your Battlesnake will choose a move randomly. Your goal as a developer is to read information sent to you about the board (available in the gameData variable) and decide where your Battlesnake should move next.

See the Battlesnake Game Rules for more information on playing the game, moving around the board, and improving your algorithm.

Updating Your Battlesnake

After making changes to your Battlesnake, you can restart your Repl to have the change take effect (or in many cases your Repl will restart automatically).

Once the Repl has restarted you can create a new game with your Battlesnake to watch your latest changes in action.

At this point you should feel comfortable making changes to your code and starting new Battlesnake games to test those changes!

Developing Your Battlesnake Further

Now you have everything you need to start making your Battlesnake super smart!

Early Development Goals

Here are some simple goals to help you develop your Battlesnake early on. Completing these will make your Battlesnake competitive against other Battlesnakes in multi-player games.

• Avoid colliding with walls
• Avoid colliding with yourself
• Try to move towards food
• Avoid colliding with other snakes

Once you have completed these steps you'll be ready to compete live against other Battlesnakes and start exploring and implementing more complex strategies.

Helpful Tips

• Keeping your Repl open in a second window while games are running is helpful for watching server activity and debugging any problems with your Battlesnake.

• You can use the print function to output information to your server logs. This is very useful for debugging logic in your code during Battlesnake games.

• Review the Battlesnake API Docs to learn what information is provided with each command.

• When viewing a Battlesnake game you can pause playback and step forward/backward one frame at a time. If you review your logs at the same time, you can see what decision your Battlesnake made on each turn.

Joining a Battlesnake Arena

Once you've made your Battlesnake behave and survive on its own, you can enter it into the Global Battlesnake Arena to see how it performs against other Battlesnakes worldwide.

Arenas will regularly create new games and rank Battlesnakes based on their results. They're a good way to get regular feedback on how well your Battlesnake is performing, and a fun way to track your progress as you develop your algorithm.

(Optional) Using a Cloud Provider

As your Battlesnake gets more complex, it might make sense to move it to a dedicated hosting provider such as Heroku or AWS. We suggest choosing a platform you're familiar with, or one you'd be interested in learning more about.

If you have questions or ideas, our developer community on Slack and Discord will be able to help out.

(Optional) Running Your Battlesnake Locally

Eventually you might want to run your Battlesnake server locally for faster testing and debugging. You can do this by installing Dart and running:

dart run

Note: You cannot create games on play.battlesnake.com using a locally running Battlesnake unless you install and use a port forwarding tool like ngrok.

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Questions?

All documentation is available at docs.battlesnake.com, including detailed Guides, API References, and Tips.

You can also join the Battlesnake Developer Community on Slack and Discord. We have a growing community of Battlesnake developers of all skill levels wanting to help everyone succeed and have fun with Battlesnake :)