Health is pretty generous but it doesn't actually matter due to the enemy placement and constant bottomless pits. In how far I got, I'd never gotten close to dying via hp drainage.
Knockback is very classic NES, but not in a good way. They don't make many games like this anymore for good reason.
Plenty of enemy placement that makes it near impossible to get through without perfect timing should you have already died and lost your sub weapon.
Aside from that though the game is absolutely fantastic, graphically it looks stunning, and matches the best of games from the era.
The enemies themselves are fine (the skeleton is pretty aggressive but it feels pretty badass to slice through all his shots), and I really enjoyed the ninjas (when they weren't kicking me into pits), they're visible enough after the first time that you can watch out for them, but just subtle enough that they can still get you if you're distracted with the other stuff on screen.
The sword slash felt great and obliterating your enemies in one quick swing makes you feel very powerful. I really wish there was a down slash of some sort, so many deaths came from needing to jump over to a platform with enemies, them edge-guarding, landing on their head and falling in a pit. The game does at least allow infinite lives as far as I can tell, and has checkpoints, but some of them work against you when there aren't any sub weapons and you have enemies right after a pit.
Out of all the games here, this probably feels the most true to the NES, and if you're nostalgic for that sort of experience, a hardcore speedrunner (or just masochistic) it'll be a perfect fit for you.
Not my game, but definitely someone's game. I cannot deny it was very well made, and the enemy placement is obviously 100% intentional to emulate that old-school kind of experience, and it does that to a T.