It is rare for me to start a project with a medium such as 'Card Game', 'Pencil and Watercolor' or 'FPS' because it's almost impossible to force creativity. The best ideas are always the ones you come up with when you're just nodding off to sleep, taking a shower, waiting for a bus, or enjoying a long car journey. Nevertheless, in the creative industry, briefs like 'Make a game about dogs' or 'Draw a character for children' are all too common in my opinion. Or it's not that they're TOO common. These kinds of requests are sometimes necessary but like I said, they rarely lead to fantastic ideas or creations.
Jon Blow did a talk on this but I can't find it for the life of me. The title had something to do Creative Burnout I think.
So I'm having starting. With the first two projects I had a set mechanic I wanted to explore and I was able to implement and experiment with it strait away. Card Games take planning but I do feel like I should already be experimenting with physical prototypes. I might do that tomorrow.