Thank you for playing it !
Right now it is "space dependant". But the term "size" could work too.
Meaning, when you draw a shape X, I simplify it and only study the points remaining of that shape against a pattern Y in it's space representation. I compute a score which is only distance between each points and compare it to a threshold hardcoded.
But this technique isn't optimal like you have guessed. I will do something better after when the rating is over and that I have a little time to spare.