It is completely innovative to the point of experimental, really.
It's non-linear, much more so than the NES Metroid. It was, I think, the first attempt at a Symphony of the Night type of gameplay on the NES. This is also the reason why Simon's Quest was criticized. It was just not Castlevania, except for the main character.
I like Simon's Quest, even with all the glitches. I wasn't able to finish it then, that's why I searched around to find a remake of it.
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Dracula's Shadow is a freeware, Simon's Quest remake. It makes use of the original NES tileset, but the coder added some other fun stuff, minus the bugs of the original version.
The truth is, I only glanced at the screenshot and decided to post it here for my own reference. I have yet to make the game run on my PC.
Hope I can make this play on my PC next time, maybe.