Game Maker’s Toolkit has released a new video in its Boss Keys series that offers an in-depth look at a game that would later have an entire genre named at least partially after it.

The latest Boss Keys video takes a look at how the levels, world, and progression in Super Metroid were designed to artfully guide players through the game without being too frustrating or too simple.

The many rooms of Super Metroid are connected from the start and progression is drip-fed to players through unlockable abilities gained throughout the game. The video maps these out through a ‘dependency chart’ that tracks how layers of new rooms, upgrades, and additional items are gated throughout the game.

Players can navigate to some of these areas that they’re not meant to be in early on in the game, but the game very clearly tells the player that they’re not meant to be there quite yet by introducing obstacles like certain doors or unique terrain that can’t be opened without gear found in other areas of the game.

Boss Keys explores how Super Metroid crafts and layers this system in the full video embedded above and, for more like this, be sure to check out the full Game Maker’s Toolkit channel on YouTube as well.