Yes, they state it on the website as well:
"See how well it does with your drawings and help teach it, just by playing."
This is interesting, because once it recognizes my drawing, it cuts me off before I finish, which would seem like it's adding incomplete drawings to the training set. Maybe it just wants examples of versions that it can't already recognize.
Yea, apparently two disconnected spoked-wheels are a bicycle now, based on the drawing it accepted from me.
it's a training set before it's a game, i'm sure. the fact that they were able to make it fun just makes it a win/win.