One, the person that said the part about the portfolio, that is true in all forms of software development and web design/development as well. It is doubly important in graphic design and simulation design. You can create nice web portfolios too. Even your own websites where you make them be a host for your portfolio.
I'll add this, which is something I regret now that I agreed to, but I can still port the code and design to another game at any point as I still have those. I created game content items as a volunteer for a company that has since even changed their own systems to not need those solutions. However, at the time of doing the ones that I allowed them to use, I had to share the code in its entirety. Nothing new there. The thing is that I didn't put my own license on the code or even get in writing that I can return to them at a later date to cash in on favors and stuff that I basically did for them. Stupid me, but hay it was volunteering and it gave me some experience.
Check out this book:
http://www.barnesandnoble.com/w/crea...=9781593572549 which can help with the digital portfolio.