This is a ROM hack of Castlevania (USA) (Rev A), created by Dragonsbrethren. It's a fan-made modification that alters aspects of the original game, potentially changing gameplay mechanics, levels, graphics, or story elements.  The '~Castlevania Retold' designation suggests it offers a reimagining or significant alteration of the original game's narrative and/or gameplay.

Castlevania (USA) (Rev A) [Hack by Dragonsbrethren v2.0] (~Castlevania Retold)

Castlevania (Europe)