Metroidvania games
The name of Metroidvania genre is a linguistic blend of two words: Metroid and Castlevania. So as you can easily guess Metroidvania games have similar gameplay as the two games. Basically Metroidvania includes platform games that are mostly based on exploration though there can be variations. The world of such games is pretty big and there is quite a lot to discover, sometimes you’ll need to find specific tools, weapons and other items or acquire specific abilities to enter doors and portals to other parts of the game. A character in Metroidvania games can be upgraded and such upgrading is a pretty smart thing to do as it will allow to face stronger enemies or discover secret locations or shortcuts.
All in all what Metroidvania should give you is: a fun character to control, ways to upgrade it, exploration based world that is both leading through the main gameplay and encouraging you to find out more about the world you are trying to conquer.