i believe that another challenge that could be done would just be reaching the goal in this level without using any of the placable blocks, i've done it and it wasn't that to do.
the corrupted halo one was easier than playing the level normally because for most of it you just had to fall, so i think that that one would be better if it wasn't playing the level backwards
i don't see why there is so many placable blocks to pick up as on my first play of the level i was usually around 8 to 10 at all times after picking up the first ones.