Unique

I think it's great that you're spending time on this, but I believe you have to change your question slightly; how can I exercise my passion, and develop myself?

As far as I'm concerned, you don't find what makes you 'unique.' You've got to find what makes you, YOU. Instead of trying to do what the colleges want you to do, do what you want to do.

As much as colleges want you to do extracurriculars, they also want you to follow your passion. So if for example, computer science is your passion, learn some coding! Sure, it doesn't qualify as an 'extracurricular' but this WILL help you, as you'd be developing yourself as a person; colleges like MIT, Harvard, Stanford, Caltech, etc., all of them want a wholistic and well-rounded person.

I'm not saying "Don't do extra-curricular" at all, but most of what you spend your time on should be in an area that interests you.

So here what you can do :

Find your hobby/passion.

Research what you can do with it and how you can develop it.

If there is a club for it, go join!

If not, use the power of the internet.

Most of all, stop trying to impress a college and start trying you develop yourself.

Hope that helps! :)

Cheers!

Tharun