So, what is the point?

So for most of my games that I've made for Ludum Dare I've always had fun and always got everything done and ready for the submissions, but I always have the same issue. It never really occurred to me (as silly as it sounds) until I watched one of Pixel Prophecy's Post Mortem videos (They're really good by the way) and he spoke about the actual GAME, I think as silly as it sounds I've always been blinded by the fact that I even made a game and that made me happy but I never asked myself "what is the objective/end game" So I pass the question off to you experienced guys and gals. What do you do to help you decide what the Objective of the game is?