Before I went on holiday I got roughly half way through the design document and its peripheral reference guides, which I'm writing simultaneously. I had spent about forty hours on the documents, that includes research time for language features and development tools. I had a read through the work I had done, to remind myself where I had got to and was unpleasantly surprised by how much I was unhappy with. While the core concept remains the same, I have made a few U turns on some fairly big gameplay systems. I also found lots of places where better descriptions were needed. So yesterday I edited for three hours, making the changes I had noted down previously.
I'm fortunate that I learned how to write good design documents a few years ago, at uni, but a refresher is always worth while. Gamedev and Gamasutra host loads of articles about doc's and even have full examples and templates. Here's my favorites...
Monolith's Claw Design doc is a great example of a professional design document.
Tom Sloper's article is a concise look at the main uses of a design document.
Chris Taylors Design document template is invaluable.
I've used Chris Taylors template with nearly every project I have worked on. It saves a huge amount of pen and paper and page formating to have so much of the document framework laid out when I start. Although thats no excuse to sit back and assume I have everything covered! The largest challenge so far, has been keeping track of points I need to expand on in later sections, and then positioning them somewhere appropriate in the design doc. So, some pen and paper note taking has been a necessity, but generally a template is a damn fine thing.
In other news, I've begun work on concept art, nothing flashy for now - just some GUI designs and a little pallet testing. I want to have a few concept pictures in the design doc when version 1.0 is published. Next time I'll hopefully be reporting on the finished design doc, and provide a detailed look at some special sections that will aid remote indie development teams.