Metroidvania

Castleroid (also, Metroidvania) is an umbrella term used by the media to describe certain Castlevania video games that borrow gameplay elements from Nintendo's Super Metroid. Games commonly referred to as Castleroids include Castlevania: Symphony of the Night and other 2D games from the series that followed in a similar style: Circle of the Moon, Harmony of Dissonance, Aria of Sorrow, Dawn of Sorrow, and the upcoming Portrait of Ruin. The term is sometimes broadened to refer to any of current series producer Koji Igarashi's games, including 3D games such as Curse of Darkness (Qualls).

Name origin
Castleroid is a portmanteau of two video game series titles, Konami's Castlevania (itself a portmanteau) and Nintendo's Metroid. The word was coined to reflect the incorporation of gameplay (particularly exploration-based gameplay) elements from Super Metroid into 1997's Symphony of the Night, and is used primarily by the gaming press and people familiar with the Castlevania franchise. Use of alternate terms such as Metroidvania is widespread in the media and fan base. However, fans of Castlevania tend to avoid this term as it places emphasis on the Metroid series rather than Castlevania itself.

Critical reception
Although the press admitted that Symphony of the Night was "laid out in a very similar configuration" to Super Metroid, it was not criticized for incorporating elements from Nintendo's game (Gamefan). In fact, the reaction was quite the opposite; the decision was praised for breathing new life into the series. "It's impressive how Konami have combined the best aspects of Nintendo's Super Metroid with their own expert character design, and knack for drama" (Computer and Videogames Magazine UK).

Subsequent Castleroids have fared well critically (GameStats.com), although the question of if they'll live up to or surpass Symphony of the Night often plagues discourses on the games (Hardcore Gamer).

Elements associated with Castleroids
Distinct features associated with the Castleroid formula are non-linear, exploration-based gameplay and power-ups. Typical gameplay involves exploring the game-world and discovering areas that cannot be accessed at the current time. Finding an item (either a key or a special ability) usually grants access to the new section of the game. Some upgrade items are needed to obtain others, lending a sense of structure, sequence, and linearity to the game. This structure is often vital in creating a coherent plot by ensuring that events that progress the storyline are triggered in the proper order.

Despite this implicit structure, industrious players often pride themselves on sequence breaking these games. One example is traversing the Underground Waterway in Circle of the Moon before receiving the Cleansing item, which purifies the poisoned water that fills the level. Sans purification, the water damages hero Nathan Graves. This obstacle was intended to prevent players from prematurely progressing to an event in which Camilla (the level's boss) reveals storyline information and subsequently obtaining the Roc Wing (an item that allows access to several other castle areas) with her defeat.

Precursors
The original Metroid and Castlevania II: Simon's Quest blazed the trail for the Castleroids. Both were based heavily on non-linear, side-scrolling exploration, with areas that could only be reached after attaining items in other areas. However, neither had the automatic mapping feature or any real semblance of plot that can be found in the Castleroids that followed. Castlevania games after Simon's Curse returned to a strictly linear, or branching-path linear, structure until Symphony of the Night.