Castlevania Legends (known in Japan as Akumajou Dracula: Dark Night Prelude, the former sub-title loosely translated to "Devil's Castle Dracula") is a 2D horror-fantasy action platformer developed by KCE Nagoya and published by Konami for the Game Boy in Japan (on November 27, 1997), North America (on March 11, 1998), and Europe (in 1998).
A spiritual successor to Castlevania II: Belmont's Revenge, Legends is a non-canonical prelude to the Castlevania series. Set in the year 1450, players control Sonia Belmont (the mother of Trevor Belmont from Castlevania III: Dracula's Curse), as she becomes the first in the Belmont line of vampire hunters to hunt down the evil Count Dracula (with help from Dracula's deserted son, Alucard).
Castlevania Legends packs in many more game mechanics than either of its predecessors did, perhaps combined. Along with the upgradeable whip and rope slide featured in Castlevania II: Belmont's Revenge, Sonia is offered the following abilities:
Burning Mode - pressing both buttons renders Sonia invincible for a short period of time, and gives her the ability to do double damage. This ability is limited to once per life on a given stage and is governed by a countdown meter.
Crouching Walk - Sonia can pass through low barriers by walking forward as she crouches. This is the same ability Simon Belmont has in Castlevania IV for the Super NES.
Soul Weapons - Sonia can use five different magical attacks, which take the place of the traditional sub-weapons in Castlevania lore and the mere two sub-weapons from Belmont's Revenge. Instead, the Axe, Holy Water, Cross Boomerang, Dagger, and Time Stopper are special collectibles that you need to find in order to get the "real" ending.
Air Control - Unlike the 8-bit Belmonts featured in games prior, Sonia has some amount of air control while jumping. There's not quite enough to allow her to easily jump onto a platform directly over her head (though it may be possible with precision timing), but it does offer the player enough to avoid some enemy contact or prevent overshooting a jump.
Castlevania Legends also offers vertically-scrolling areas, where the majority--if not all--of the previous two games achieved vertical progression screen-by-screen.
The level design is mostly linear but has some path divergences where you can find the aforementioned special collectibles, one-ups, et cetera. These divergences are more than single-screen hidden areas, such that you'll veer off the beaten path for a short distance, though not enough to get you lost. There are also trap areas triggered by striking certain candles, landing you into a pit of respawning zombies that you must continue to slay until they're all gone, at which point you're returned to the room above.