Wow, its an actual hack. o_O I must say I wasn't expecting this at all. I only played the first few levels and I must say the music is awesome, but its another hack with that plumber again, so 0/10 Bwahahaha!
I don't suppose you are releasing any of it are you?
I'm finding a few conveyance problems here and there, for example when teaching the player to use the blue block squares. Also, the graphics' contrast really confuse me. There's a few examples of tiles I think I should be able to stand on, but can't and vice versa.
... and just as I type that, I play further into the level to find an example of it done much more properly;
It's alright. However, there are some significant flaws, as pointed out by Mandrew earlier. The level design was by far the best aspect of this hack, and the foreground graphics were also quite nice (hand drawn, I believe?). The music was fine but, in my opinion, wasn't anything spectacular.
This is pretty enjoyable. I couldn't find any issues that hindered the hack, which is cool, and the giant throw blocks are very unique. I laughed at the messages, but the one in special is at end of the fortress after those nets; killing the background is something appropriate in that case.