I played this awhile back when it came out, but forgot to comment! I went ahead a gave it another spin now to see if I could make it further.
First of all, the pixel art is AMAZING! The amount of detail and life squeezed into the low resolution is outstanding.
I love the morbid concept of running around and blasting enemy corpses at your foes. Loading and shooting yourself is really funny too.
I found the game really difficult. I gave it several plays the first time, and only made it toward the 2nd obelisk. Today was no different. I think the core critique I have is that moving the cannon is really difficult. Loading and blasting the cannon feels pretty satisfying, but pushing it around feels clunky and frustrating.
I'm not really sure what the best solution would be though, because precise control would probably make it TOO easy. Made there's a middle ground somewhere in there.
Still, this is a really impressive game... I'm amazed at how much you got into this tiny canvas, and how complete and polished it feels!