This game, while having a good start, is... well, just bad. It relies entirely on fake difficulty (Such as several jumps requiring perfect timing) to extend a meager five minutes into thirty or more. All the puzzles were solved within just a few seconds (Jump here, then there, jump phase phase jump phase phase jump there...) and it was only the execution of the solution that took time. The invisible blocks just made me nervous, but the phasing WOULD have been a fantastic idea... Ever heard of Shift? I like that game. Press the button, you flip into the negative space. This could have been at least as good as shift if the phasing had been more developed and less perfect-timing-based. As it was, it was just more of the same stuff that required you to have the most precise timing. It didn't make it enjoyable. It made it annoying. If you really want to make a game that relies on fake difficulty for content, you will NEED to go all out. Look up I Wanna Be The Guy. That was a good fake difficulty game... but only because it was so ridiculously over-the-top.
You want to know how to make it better? First: Focus on phasing. It's your unique idea. Use it in every puzzle. Second: Puzzles. Make them puzzles, make it seem like this might work, but no, that doesn't work, maybe this way? Or if I flip back here and... Success! Keep it a mystery as to whether or not it'll work right up to the last second (But don't have sudden random invisible instakills right at the end, as that's more fake difficulty).