Happy Birthday Gamedev!
The big ZYNGA logos are because it's a pad of free sticky-notes I got at a game conference a couple of years ago. Stickies and pencils are the only design tools you need.
And yeah, this is kind of a joke. But it does give you a bit of a feel for design. If you're a one-man shop and you have a simple design and you're confident in your ability to implement it, then don't spend much time on design. I wrote my first computer game almost 30 years ago, so design documents come second to getting an idea working while it's still fresh in your mind.
My bug-fixing process is the same. I am never more than two feet from a pad of stickies, and when I find ANYTHING, I quickly write it down. You'll be surprised how many ideas are lost between the time you switch from the game running on the screen back to your text editor.
BTW, "Kismet" is also trademarked, so I went with "Destino". "Kismet" is the Turkish word for "Fate", so I went with the Italian word for "Fate". Get it?
And I ended up dumping the three-column mode. Made the game too long and it also made the cells too small for dinky iPhone and Android screens.