Ctrl is a poor choice for actions especially when it needs to be pressed in concert with other keys.. Ctrl+S is save. Ctrl+D is Create a bookmark... Ctrl+A selects all.. Indeed at least in Google Chrome the Control + D function will not allow the player to make the action. This breaks the game.
That aside the controls don't make the game difficult, just mildly annoying. Needlessly annoying controls and controls that cause problems with the web browser /break the game aside the game doesn't actually seem very puzzly. Everything I have run into is very straightforward to this point where you just move down the line of buttons. It is OK but nothing that makes me care to replay it or try to find a way around the control problems. I have no idea how much of the game I have remaining, it broke at the first level with levers (for obvious reasons). I probably would have given it 3 stars based on what I had played if it didn't have a game breaking bug/feature.
Get rid of the bad controls and add some puzzles to the puzzle game and it may become something really good.