We tend to learn more from our failures than our successes. If you're not "failing" on a regular basis you're not trying hard enough, so kudos for taking the gamble. Definitely put it on your app. What you have to show for it (aside from the competition win, which is great) are the lessons you've learned from the experience. Sit down, articulate all that you've learned from working on the startup (e.g. working on a team, leadership, etc...), and write it down. This should hopefully give you some good stuff to talk about on essays and/or interviews to show how much you've grown from the experience and how it could help you in your future endeavors.