Big fan of level 8, it really made you think with the block on the right about how the edge of a screen is not an edge but a portal. Great puzzle
Big fan of level 10, you had to take the block in gravity and use it to get back over that litle wall on the ceiling and also run toward the key so you could make it. Then take the block and put it on the pad and finish. It was a great teaser.

Level 5 bypassed the spikes with a good jump and just went to the exit.

My main problem with the game is actually the 2d. Its the best part about it too. The block gets stuck on walls and in strange places sometimes, on level 3 or 4 i think i had to reset because of it Mainly because the block can be accidentally pushed and you have to restart a puzzle over sometimes because of it. I did this on level 11 and it was just a little annoying but having a side step button or some clear way to walk through the block would be great.

Overall I liked it. Great job.