createNewGamelog.js

Gamer.findOrCreate({username:'whiplash'})
  .then(function(user){
    return Gamelog.create({gamerId: user.id});
  })
  then.(function(gamelog){
    return Game.findOrCreate({title: 'Star Citizen'})
      .then(function(game){
        gamelog.gameId = game.id;
        gamelog.save();
      });
  })
  .catch(console.log);