I am loving this game. It totally reminds me of Metroid and Super Metroid, but it has some very unique elements as well, so it does not feel like a clone at all. Very original gameplay and easy to learn, but quite challeng to play!
I did not have any trouble playing from a technical standpoint. It was challenging at times, for instance the "breakout" part. However, each time I played, I felt like I was getting a bit further, and it was a fun challenge. For me it had the right kind of difficulty. I did make it to the end, and I was intrigued by the hints of what was to come.
My only small concern was the shift boost thing. Maybe just re-assigning the key would have been enough, but I feel like it would have been better as a mouse click, or maybe space bar.