What do I do now?

I'm a sophomore currently majoring in IT, and I have absolutely no idea what I want to do. I switch between wanting to focus on security, to mobile development to system administration to game development. It seems like everyone around me has a clear-cut plan of what they want to do after their education, such as getting certain certifications, or taking a job where they have been an intern. I really don't to leave college to become part of a big corporate object, I'm not even sure if I'll be able to adapt properly to such a different culture.

Right now I've been working on a number of side projects at my own leisure, and one in particular is taking on a relatively impressive form. Without going into boring details, I plan on making a comprehensive 2D engine, with it's own very robust asset creation programs and level editor, which can export to Windows, Mac, Linux and (with a little more work) Android. It's one project that I'm very passionate about. I'm thinking of creating a start-up off of it, but putting myself out there in such a competitive market terrifies me, especially because I know nothing about how to run a small business.

I have a professor who has told me that starting a company as early as possible is the best way to both progress in the business world, as well as financially and in terms of experience. For me, it seems that if my product becomes even remotely successful, I might be able to dodge the "corporate grind" that I am dreading. Seeing this project's completion before the end of my education seems to me to be the only way to avoid my fears. Is this a good idea? Or am I being far to melodramatic about my future to think that one idea cab determine the outcome of what may very well be the rest of my life.

Thank you all so much for making this community what it is, and I look forward to your responses.