KNOCK

Knock, Knock, Knock. Get the door open and go through it! Stage cleared!

Every level provides a unique challenge with a creative combination of objects: They may rotate, swing, wave, bounce, fly over or rock&roll.
Watch carefully, plan ahead and go for it. Make sure to knock on them for a certain number of times to open the door. No more, and no less! 
160+ stages are ready for you. How many of them can you go through? Try now!