The last time I was over at a friends' house I played this game, Super Ghouls 'n' Ghosts. He said it was one of the hardest games he'd ever played, and that it was tough. So I played it, and it took me nearly an hour to beat the first level. This game is hard. I'm currently emulating it, and it only took me about 15 minutes this time. The second level is really BS though. Since there's this rafting part and all of the enemies' hitboxes are insane. Here's some gameplay if you haven't seen it:
And here's one of the rafting section (skip to the 2 minutes mark):
And here's one of the rafting section (skip to the 2 minutes mark):