1986 · Action Platformer · MSX
Vampire Killer was the MSX version of Castlevania, but with different level design, non-linear exploration, and key-based item collection that predated Symphony of the Night's exploration formula by over a decade.
While the NES Castlevania was a linear stage-by-stage action game, Vampire Killer on MSX required collecting keys to unlock doors and had non-linear room connections. This exploration-based structure anticipated the Metroidvania design philosophy.
Vampire Killer was developed by Konami's MSX division alongside the Famicom Castlevania. Both games shared visual assets but had completely different level designs.