Metroidvania

also known as (for better, or worse): Castleroid, Metrovania

The name 'Metroidvania' originates from the beginning of the Igavania era of the castlevania_series|Castlevania series, when the games seemingly took inspiration from the Metroid series, and became more exploration-based. The term has since become a common descriptor of any game in that style: a 2-D platform game with adventure game elements.