npm install --save-dev babel-cli

# package.json
{
  "name": "mazerunner",
  "version": "1.0.0",
  "scripts": {
    "build": "babel src -d lib"
  },
  "devDependencies": {
    "babel-cli": "~6.7.7",
    "babel-preset-es2015": "~6.6.0"
  }
}

# building
npm run build

# install the cli and this preset
npm install --save-dev babel-cli babel-preset-es2015

# make a .babelrc (config file) with the preset
echo '{ "presets": ["es2015"] }' > .babelrc

npm run build && node /Users/raganwald/github/mazerunner/lib/index.js


*--*--*--*--*--*--*--*
|     |              |
|     |              |
*  *--*--*  *--*--*--*
|  |        |  |     |
|  |        |  |     |
*  *--*  *  *  *  *  *
|     |  |  |  |  |  |
|     |  |  |  |  |  |
*--*  *  *--*  *  *  *
|  |     |  |     |  |
|  |     |  |     |  |
*  *--*  *  *  *--*  *
|           |     |  |
|           |     |  |
*--*--*--*  *  *  *  *
|  |     |  |  |  |  |
|  |     |  |  |  |  |
*  *--*  *  *  *--*  *
|                 |  |
|                 |  |
*--*--*--*--*--*--*--*