Damn, I used to play Zanac. I loved it! The music* is good, the action is intense AND proportional to your power (if you get very high-level weapons very soon, more enemies will appear at same time than if you did not - of course, some areas are always filled with enemies).
I don't remember well, but maybe I got at most at level 8 or 10. Well, I remember I reached some level with space background, and I remember I died there some times.
I have a question: would this "reset" thing work also on a real NES machine?
My suggestion for new screenshot: one of the last frames, where it displays 35 lives; or one of the frames with tons of bullets
*
OverClocked ReMix has some very nice remixes of Zanac music (I can't say so about other games remixes). Believe me, the title music and first stage music are much better than the last level music.