(UPDATE: There is a greatly improved version of the game here)
I found a doodling game which is basically identical to what I’m doing in my head all the time. Yes, I draw lines in my head and imagine a little dude jumping or sledding on them. The game is actually pretty challenging and addictive (the little guy falls off his sled pretty easily). Here’s what you can do if you have a LOTof time on your hands: