Simple design, decent movement quality. Difficult firing pattern (one shot per jump?) also, was able to kill creatures before the screen revealed them (bullets connected with monsters I never saw but heard dying offscreen). Also, found myself in a dead end with no way forward but to backtrack and be killed. Boo

The graphics remind me of flash games from 2004-2008 which is a nice welcome but what isn't a nice welcome are the controls. The movement feels sluggish at best, and having J as the fire button makes my hands feel really cramped when jumping and shooting. I feel like L would have been a better choice for this type of control setup. The green coins as far as I'm concerned don't serve a purpose whatsoever. Maybe collecting 20 of them can earn you a free hit point?
Overall I think this should use a bit more work before it can be passable by today's standards.