game.js

var fs = require('fs');
var Steam = require('steam');

var bot = new Steam.SteamClient();
bot.logOn({
  accountName: 'username', //Username
  password: 'password', //Password
  authCode: 'code', // Steam Guard
  shaSentryfile: fs.readFileSync('sentry')
});

bot.on('loggedOn', function() {
  console.log('Logged in!');
  bot.setPersonaState(Steam.EPersonaState.Online); // to display your bot's status as "Online"
  bot.setPersonaName('Morgiana'); // to change its nickname
  bot._send(Steam.EMsg.ClientCurrentUIMode | 0x80000000, Steam.Internal.CMsgClientUIMode.serialize({
    uimode: 1
  }));
  bot._send(Steam.EMsg.ClientGamesPlayedWithDataBlob | 0x80000000, Steam.Internal.CMsgClientGamesPlayed.serialize({
    gamesPlayed: [{
      gameId: 570, // game AppID
      gameFlags: 5120
    }]
  }));
});