Pretty fun concept. There were a couple frustrating parts due to lack of sound or feedback, when I pressed a button there was no "door sound" to tell me a door opened. This was really frustrating when It took me a few tries to tell that the button opened a timed door, as there was no audio or visual indication that the door opened. As a good reference for this kind of puzzle game, Check out the buttons and doors in Portal, at a minimum, they have the little lights along the walls floors and ceilings that light up when a button is pressed and you can follow that wire/light trail to the thing it's connected to. Beyond that, the backtracking to the beginning of the level for the hand arm so I could press the end level button was extremely annoying, having an extra one at the end, or not needing the hand arm to complete the level would be better.