Dooors2 Level 29 Walkthrough:
1. The door wants you to figure out what level it is.
The level is 29. Tilt your phone/device to the left and you'll see a round white hole cover sliding around.
Block the left hole and change the number to 2 (press it twice). It'll look like a strange symbol but if you cut it in half down the middle, it's actually two 2's.
2. Block the right hole and change the number to 9 (press it 9 times). It'll also look like a strange symbol but cut in half, it'll be two 9's.
Block the middle hole and press the door to open it.