How Metroidvania Became a Gaming Genre.

Source

Metroidvania is a portmanteau of two legendary gaming franchises; Nintendo’s Metroid and Konami’s Castlevania. Both series started on the NES, in 1986, as side-scrolling titles. Metroid focused more on exploration while Castlevania was a straightforward platformer akin to Super Mario Bros. and Mega Man.

Source

Castlevania would begin experimenting with freedom of exploration in Castlevania II: Simon’s Quest on NES. However, the remainder of the series — until 1997 — would stay true to the original platforming formula of the first game.

Rondo of Blood began to take steps towards more exploration with multiple routes in stages. Source

Meanwhile, 1994’s Super Metroid took the exploration aspects to the next level. Metroid II: Return of Samus introduced the Space Jump and Spider Ball abilities to allow you greater freedom of exploration. Super Metroid capitalized on these elements by introducing a map. This map allowed you to keep track of your progress.