There’s just something about Zelda‘s dungeons that keeps you coming back for more, but what exactly is that je ne sais quoi that makes the dungeon-crawling element of Zelda so memorable? Enter Mark Brown.

Mark Brown has been making a series called “Game Maker’s Toolkit” on YouTube for the past two years, making it his full-time job. He covers a variety of games — many of them Nintendo properties — but one topic he’s always wanted to cover was The Legend of Zelda and its dungeon design. What makes a dungeon tick? Why are they so enjoyable? And what has changed about the way Nintendo makes dungeons over time?

Because there are so many Zelda games, Brown knew that it would take a good amount of research in order to figure out those answers. As a result, he’s created a subseries on his channel called “Boss Keys.” Roughly every month, he plays through the next Zelda game in the series, writes up his findings, and then not only talks about but also demonstrates why the dungeons of the particular game are good or bad.

For example, you might not have known that nearly every dungeon within Twilight Princess has a roughly identical dungeon layout. Or you might not have realized that the dungeons of The Wind Waker are much simpler than they feel because they completely eliminated the need to backtrack by constructing huge loop-like pathways or that at no point in the game can you have more than one key at the same time. Or maybe you didn’t realize that Ocarina of Time never lets you choose where to spend a key as there’s only one locked door available to you at any given time, But Mark Brown, through his research, reveals these fun facts and more. Whether you’re into game design or not, “Boss Keys” is chock-full of Zelda trivia and astute observations.

So far, Brown has done episodes covering A Link to the PastLink’s AwakeningOcarina of TimeMajora’s Mask, both Oracle gamesThe Wind WakerThe Minish Cap, and Twilight Princess. His next video covering Phantom Hourglass (and possibly also Spirit Tracks) is due to come out either in February or March. Presumably after these, he will continue on to cover Skyward Sword and A Link Between Worlds, although whether or not he’ll tackle Breath of the Wild is anyone’s guess.

You can view his series “Boss Keys” on his YouTube channel as well as the many other videos he’s done for “Game Maker’s Toolkit,” and you can support his research by donating to his Patreon.