So, I've been really trying to beat this game lately, and man, this game isn't that easy.
The first 4 levels are super easy, but when you get to the underworld part of the 5th level, the difficulty jumps way the hell up. It can be quite frustrating. For the longest time, I was playing for about a half hour to get to the 2nd half of level 5, but I've lately been using the debug menu and just skipping to level 5.
The only problem is, I still have to grind for money to be able to afford the Jewel Sword (2400 gold), and when I get to the underworld, I need to grind for hearts. I could give myself more hearts and money in the debug menu I guess, but there is a limit to how much I'll "cheat", lol.
I normally hate using continues, which makes this game especially difficult when you only get 1 life. Sure, the first 4 levels are super easy, so the game seems easy at first blush, but man, things start to get harsh late in the game.