Fun Fact: The Nintendo Power cover for Simon's Quest showed Simon holding Dracula's dismembered head, which spurred complaints from parents.
Castlevania II took a decidedly-different form than the first game in the series. Where the original was a linear platformer, Simon's Quest was more of an adventure. The goal was to retrieve the parts of Dracula's body and the Magic Cross to finally destroy Dracula forever and remove the curse that would otherwise kill Simon.
Players traveled through a side-scrolling overworld as they sought the six mansions that contained Dracula's remains and the Cross. There were towns along the way where players could spend accumulated Hearts on items and equipment. Townspeople would also give Simon hints or clues. Hearts were not only a currency for purchase, but also served as an experience mechanic. Simon would level up and gain additional health with each new milestone of heart collection.
The mansions themselves were more similar to the first Castlevania than the rest of the game, but featured some very large main rooms off of which the rest of the mansion branches. The parts of Dracula's body that Simon recovered were also used as equipment that gave him new powers or abilities.
Simon's Quest had a day/night mechanic that increased the frequency and strength of enemies at night, and also removed the ability to talk to townspeople as the streets were packed with zombies. There was no way to hide out from this mechanic. Players always had to face the night cycle, such that the transition signaling the end of daylight could be extremely foreboding if the player was far from the nearest town. The zombies were much easier to deal with than the night creatures in the wilderness!
There were three different endings to Simon's Quest, based on how long it took players to beat the game.