I'd say the pace was fine for this game as it stands. I had a couple of brief moments where I had to think to get the next unlock, but nothing onerous at all - just made it feel more like a game and less like a pure art piece, which was all to the good. Maybe for a fuller project it would make sense to slow things down slightly, but that might naturally happen anyway if you are broadening the scope significantly.
I look forward to seeing your future development of it!