A simple prototype with interesting mechanics, but needs more polish. Due to the fact that the rhythm display itself is shifted to the bottom of the screen, and not tied to the cursor, it becomes difficult to understand the rhythm, you have to grope for it, which is frustrating. (You can make the beat display part of the environment, like wall ripples, but anyway it should be more readable then current version.
It's also worth adding an effect or a specific color when exactly the beat (placement window) occurs. The current display is not enough). Also, the camera movement did not work for me, so I could not complete the first level.
One more thing, the easiest way to complete the levels is to stop the cube on a jump tile or between 2 gates, then build a further route, and then release it from a trap and repeat. With such gameplay, the game feels very frustrating, as the rhythm aspect becomes a mere hindrance. It is maybe worth somehow turning off this preplanning feature or making it more difficult to execute in order to make the game more interesting.
It is also worth considering expanding the window where the player can place the object, since the current window is too small for starting levels. For example, you can look at OSU, and its 1-2 star circles and their bit and window.
But in general, a very cool idea and not bad execution for a prototype, but still there is a lot of work to be done.