Pretty boring shitshow...
It nothing more than a string of far away placed enemies in hard to reach places.
It's not difficult, there just are'nt hardly any lives. That's not hard, that's just trying and trying for a lucky bro - annoying rathe than challenging.

Tried it on Hard, preferred it on Normal.
Honestly, a lot of the level design was nice- I loved your building shapes, and good use of verticality- but the long horizontal sections filled with enemies (particularly green shirts)- essentially, difficulty by way of forcing me to grind through a lot of health.
Could use some enemies on roofs of buildings- the roof was often the 'easy way' through some of your horizontally aligned buildings.