I recently found a stack of 3 x 2.5" cards -- the prototype for a pirate-themed children's card game I was developing several years ago, back when I was in a pirate-themed children's band. It was a lot of fun to remember what I was going for with the game, and I think it has potential. I plan on developing it further over the next couple of weeks. If only it didn't require about 60 individual illustrations.
But aside from the game itself, finding it made me realize something -- I really need to start taking notes. Of game ideas. Of decisions made in development, and of the math workings of particular mechanics. So I opened up an old packet of Field Notes notebooks, and started filling it out. One idea, concept, or mechanic per page. It's been delightful.
UPDATE 1/2019: Looking back on this post from five and a half years ago, I'm quite proud that I've kept up the Field Notes process. I now go through one notebook in about three weeks, and have all sorts of colour-coding and shorthand practices.