Usually, I write a design doc before making any game. Actually, I often write design docs for games that I will never make! I erase them after I figure out it's not worth keeping them around. For the PetJam, I just am working on the game. I assume that's how game jams work, right? You have a limited timeframe to make something, so the luxury of time isn't really there. I suppose in such a situation, skipping the design document and going straight into coding isn't a bad idea!
So my current VIRTUAL PET is called EJBU-ADDY - I changed the I in VIRTUAL for Interactive instead of Intelligent - and here's a screenshot of what the game might look like when you boot it! ADDY's mouth moves when it talks and his eyes will follow your mouse cursor around. The middle box will be used for you to reply to your PET and the big box at the top right will be for your PET's stats. I'll be working on that tomorrow!
No design doc, but still, I have so many ideas I'm writing them as comments into my main C# file. This game probably wouldn't expend very well past a certain point since everything is written in just one class, but I want to get it done, not really have anything fancy, code structure wise ;)
Time spent working on VIRTUAL PET: 4 hours