Okay, not a writing game, but this is a great resource I had to share:

Over the past few months, Steve Saus has been slowly posting the step-by-step process for creating an ebook from scratch, without a magic converter - it's not as hard as it sounds, and his instructions make it possible even for those who aren't comfortable with these newfangled computer things. Example post here.

He's now pulled the posts together into a how-to book that he's selling for US$9.99 from Amazon, Barnes & Noble and his own site. If you're considering making your own ebooks, this is definitely worth the price.