Rating issues
The most notable games in this collection contain violence towards non-detailed human-like characters and fantasy creatures. Generally, characters that get hit simply flicker and disappear.
Other issues
The games Castlevania and Castlevia II: Simon’s Quest have a haunted house setting, featuring depictions of vampires, ghouls and the like. The dated graphics and general lack of impact of these potentially scary elements, make it so that a separate fear-description is not in order.