Joris Dormans created Machinations, which I have previously written about, and he also described the "Mission and Space" pattern, which divides the game mechanics into two parts. The spatial part is similar to a maze, and has within it special spots that enable progress in the mission part, and some edges within the spatial part are locked, requiring some degree of progress in the mission part before the player can take that route. The mission part is usually partially ordered (there is no way to lose progress), and may simply be a linear chain. Machinations, and the Mission and Space pattern in particular, may have informed Joris Dormans's game "Unexplored".
By transliterating a dungeon generated by Metazelda into Machinations, it is easy to see how it divides into mission and space structure - and even within that, you can see some substructure of the mission part, which is divided into an inventory (of keys) and a switch which can be toggled.
Of course, it is not a coincidence that these two tools, Dormans's Mission and Space design pattern, and Coxon's Metazelda fit together so well: they are both based on carefully studying Nintendo's Zelda series in general, and possibly A Link To The Past specifically.
What is not shown in this diagram is that there is often an ongoing minigame consisting of fighting off enemies in each room, and keys are generally not keys, they are tools like the hookshot and the pegasus boots, which are used in the fighting minigame as well as their large-scale function to unlock routes. This effectively uses the entire mission-and-space structure as a slow tutorial. That is, its function is to space out the introduction of the fighting minigame mechanics.