Level 4 of the Annex in 100 Floors is probably one of those floors that will want to make you throw your device against the wall to see if it actually makes any sound. When you begin Level 4 you will notice a stick man sort of drawing in the middle with music notes and a guitar. There is also a drum right at the bottom of the screen and some dots above the door. Your task is try to follow the beat until the end – which is totally not hard, but not easy as well.
You are recommended to restart your level with the restart button at the bottom right if you fail the first time. You need to tap the screen according to the dot on top of the screen and when you get it correctly you will unlock the door on Level 4 to level 5 in the Annex of 100 Floors app game.