How do you know if an idea is worth pursuing?

This is a general question, but I will give a specific example.
Not to long ago, I decided to step out of my comfort zone and put an idea for an app, (a game based on doodling), out into the world. I put my idea on a brand new crowdfunding site specifically designed to help raise funds for the development of applications.
I got a good start, but as the time ran down I realized I was coming up short. Unfortunately, my idea was not chosen for development.
The fact that my app didn't make it could have been a combination of things, my network was not big enough, the crowdfunding platform was to new, I may have not leveraged social media effectively enough, or the idea was just simply not good enough.
So my question is, how do I know if I should try to pursue this idea? How does one know when it is a good idea to pursue any idea? Many fail several times before they succeed, but how do they know it is worth trying again?
I look forward to hearing the communities thoughts on this.