The same happened to me, on a bunch of old diskettes I found a computer game I wrote more than two decades ago.

http://www.michielovertoom.com/software/risky-software-archa...

It's revealing to look at source code you wrote 20 years ago. For example, back then I was already using the 'banner' indenting style for C and C-like languages. I picked this up from the book Software Tools, by Kernighan and Plauger, a book which has been formative for my programming education.