perfectsquircle/snek

A technical challenge

snek: a technical challenge

Forked from coalman/blessed-life

Getting Started

Installation

Clone this repo to a nice spot on your computer. Open a terminal emulator and cd to the directory.

If you're on Windows, cmd.exe, PowerShell, and git bash all work fine. On Mac OSX, Terminal.app will do.

Make sure you have node.js properly installed. Then use npm to install:

$ npm install -g

Running

You can start the program by opening a terminal and entering:

$ snek

a turns left. s turns right.

There are many command line switches that can be used (use -h or --help for more information).

To exit the game, press esc or q

Challenge

The technical challenge is to make a bot that plays the game of snek. The bot will have information about the whole game board. There are only two moves that can be made: turn left and turn right. The snek will continue moving in a straight line if no move is made.

To submit a solution, email me your implementation. Your solution may not be run against the provided board, so don't make any assumptions!

If I receive three or more submissions I will pit them against each other in an epic snek battle-off. Each bot will play in a playoff-style bracket, with each round being best-of-three games. Ties are discarded.

You may find it useful to use path-finding algorithms for your bot. I encourage you to use PathFinding.js:

http://qiao.github.io/PathFinding.js/visual/

If you're super ambitious, it will be helpful to read about elements of game theory, such as the Nash Equilibrium and Best Response.

Writing a bot

Start by copying the provided bot, ai/example.js. Give it an awesome robot name. The bot must only implement a single function: getNextMove. It should return "left" to turn left, "right" to turn right, or nothing to keep going straight.

The getNextMove function is called once per game tick. It receives three parameters: game, player, and opponent. The game object contains the current game state and looks something like:

{
  "board": {
    "width": 50,
    "height": 25,
    "cells": ...,
    "apple": {
      "x": 28,
      "y": 14
    }
  },
  "players": [
    {
      "name": "Naïve Norman",
      "snake": {
        "path": [
          {
            "x": 10,
            "y": 5,
            "direction": "S"
          }
        ]
      },
      "controller": {
        "name": "Naïve Norman"
      },
      "score": 0,
      "status": "ok",
      "color": "green"
    }
  ]
}

Cells is a 2D array of cells that represent the fixed parts of the game board. These parts are defined in Elements.js. It looks something like:

[
  ["W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  ["W","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","B","W"],
  etc.
]

You can dig into the code to see the interfaces of these objects. The player parameter represents the "player" that the bot is, whereas the opponent parameter is the other player.

Running the game

Player 1 and player 2 are specified by the first two parameters to snek. k is a shortcut for the keyboard. To load a bot, give the filepath to the bot. For example, to play against the a bot:

$ snek k ai/example.js

To pit a bot against itself:

$ snek ai/example.js ai/example.js

To load a specific map, use the --map option.

$ snek ai/example.js --map maps/eleven.json

Debugging

Visual Studio Code has a very good debugger for node.js, and is also a great editor for working on your submission.

To launch the debugger, download and install Visual Studio Code, open your working copy of snek, then press F5. Alternatively, open the debugger sidebar and click the green play button. The command line options can be configured in the .vscode/launch.json file. See "Debugging in Visual Studio Code" for more information about debugging.

Logging and such

console.log calls are redirected to the debug window, which can be toggled with F12, however this method is kind of slow and buggy. To redirect logging to a file instead, use the --log option. Internally this uses a log instance.

$ snek ai/example.js --log path/to/log.txt

You can pause the game ticker by passing -p (or using the p key), and then manually advancing the ticks with space.

$ snek ai/example.js -p

This can be useful for debugging. Also useful for debugging is modifying the speed at which the game runs. Using the --speed flag you can specify the number of milliseconds per game tick.

$ snek ai/example.js --speed 500

Rules

Your bot may READ any information provided to it about the game board. It may not:

• Modify any game state.
• Modify any player state.
• Pause or excessively delay the game.
• Attempt to subvert or otherwise sabotage the normal flow of the game.