Needs a zoom feature, the puzzles on level 3 have tiny blocks. The line backtracking is also sometimes pretty annoying, I still can't figure out what the dotted line is supposed to do.
I enjoyed the first two levels though.
The hard badge was possibly the easiest hard ever that I can recall. Being able to get the badge by completing the songs on easy is just a bit too easy.
Btw: Strafe is better than power arrow by a lot because of knockback....
Your arrows have a chance of knocing the enemy back a little if you hit above a certain percent of their HP therefore it is easier to win with.
And you get the 4th tier at lvl 70 with something like 250 Sp spent on previous thingys.