seed.js

const firebase =  require('firebase')

// Initialize Firebase
var config = {
    apiKey: "AIzaSyDdcqFO73-rCHWM5QNI0aPy3cr5-HBfZIM",
    authDomain: "captar-d200a.firebaseapp.com",
    databaseURL: "https://captar-d200a.firebaseio.com",
    projectId: "captar-d200a",
    storageBucket: "captar-d200a.appspot.com",
  };

  firebase.initializeApp(config);

// create game session
let gameSessionKey = firebase.database().ref('GameArea1').push().key

// from seed.js fed into Firebase
let flags = [
    {
        flagId: 1,
        team: 'red',
        startLocation: { latitude: 40.703295, longitude: -74.00845 },
        isTaken: false,
        currentLocation: { latitude: 0, longitude: 0 },
    }, {
        flagId: 2,
        team: 'blue',
        startLocation: { latitude: 40.703414, longitude: -74.008663 },
        isTaken: false,
        currentLocation: { latitude: 0, longitude: 0 },
    }
]

let players = [
  {
      playerKey: "-Kw6WMuMon0sLlAvdwD0",
      playerId: 1,
      location: { latitude: 40.703394, longitude: -74.008622 },
      team: 'red',
      hasFlag: false
  }, {
      playerKey: "-Kw6i3o4waw4nvoMGalr",
      playerId: 2,
      location: { latitude: 40.703441, longitude: -74.008713 },
      team: 'blue',
      hasFlag: false
  }, {
      playerKey: "-Kw6ia9oZqCwG-09MyAP",
      playerId: 3,
      location: { latitude: 40.703325, longitude: -74.008456 },
      team: 'red',
      hasFlag: false
  }, {
      playerKey: "-Kw7D5kZNpnIYXeDO6Sv",
      playerId: 4,
      location: { latitude: 40.703258, longitude:  -74.008663 },
      team: 'blue',
      hasFlag: true
  }
]

let game = {
    gameId: 1,
    gameFirebaseKey: gameSessionKey,
    flags: flags,
    players: players
}

firebase.database().ref('GameArea2').child(gameSessionKey).set(game)
    .then(console.log('success'))
    .catch(error => console.log(error))