This game is really cool and the concept of this game is superb. I really like the way this game has been implemented and presented, everything is just right into the place, the difficulty ramp-up is quite nice, the level design is quite awesome, and every other thing is good enough to enjoy. However, I did miss the audio and the game felt like it was too flat, which you can bump up using some visual effects, and a slight screen shake. Apart from that I really like minimal design, so well done.
Will be looking forward to your future projects for more such awesome content.