Distinct features associated with the Metroidvania formula are side-scrolling, exploratory, action-adventure gameplay, power-ups, and a map that is filled in automatically as the player progresses through the game.
A strong element of this genre is that the map is largely contiguous, offering no breaks in play aside from the occasional load screen. Some purists refuse to acknowledge a game as a Metroidvania unless it meets this criteria though others will include games which feature small breaks in play, such as Clash at Demonhead.