Castlevania II: Belmont's Revenge

The second Castlevania game for Game Boy. You play as Christopher Belmont again, but this time, Dracula has kidnapped his son, Soleil Soleiyu Belmont. Has smoother gameplay than the first GB Castlevania, and also (uniquely for the series) has a level select feature at the beginning, reminiscent of the Mega Man series (so the first four levels can be played in any order).

Belmont's Revenge provides examples of:

 * Auto Scrolling Level: The bossfight against the Skeledragon. Because of Christopher's slow walking speed, this battle easily becomes a slugfest.
 * Blackout Basement: One level contains a scene in which the lights go out constantly. The quickest way to keep the lights on is to throw holy water on the ground.
 * Or to not whip any candles in the room, keeping the room lit.
 * Brainwashed and Crazy: Soleiyu Belmont
 * Difficulty By Region: The Boomerang Cross is only in the Japanese version while the Axe is only in the American version. Which version is easier may therefore be a matter of opinion.
 * Dual Boss: Plant Castle and Cloud Castle bosses.
 * Meaningful Name: Soleil is the French word for "sun." Becomes a clever Mythology Gag when you remember the famous line from Castlevania 2: "The morning sun has vanquished the horrible night." 
 * Puzzle Boss: Dracula is kinda this in this game, because all of his movements are predetermined, the battle will always play out the same, and the player only has to seek out the safe spots where he can't be hit by Dracula's Sphere of Destruction move.
 * Revenge of the Sequel
 * Spike Balls of Doom: In Cloud Castle