Editing Mystery of the Castle?

{{more images|At least one more screenshot of the level itself}}
{{level infobox
|code=Secret 2
|image=[[File:Mystery_of_the_Castle.png]]
|game=''[[Yoshi's Island: Super Mario Advance 3]]''
|before=[[King Bowser's Castle (Super Mario World 2: Yoshi's Island)|<<]]
|after=>>
|track=Castle & Fortress (''SMW2:YI'')<br>[[File:SMW2YI Castle and Fortress.oga]]
}}
'''Mystery of the Castle?''' is the Secret Stage of [[World 2 (Super Mario World 2: Yoshi's Island)|World 2]] in ''[[Yoshi's Island: Super Mario Advance 3]]''. Like every other Secret Stage, this level's playable [[Yoshi (species)|Yoshi]] is the [[Yoshi|green Yoshi]].

==Layout==
The level starts out with [[Yoshi]] going right-to-left over a few long pits of [[Spike Trap|spike]]s, while avoiding several [[Fang]]s. After that, the player finds an [[Egg Block]] and a [[Warp Pipe]]. After going through the Warp Pipe, the player finds a hidden [[Winged Cloud]], and a maze of bridges over [[lava]]. Eventually the player finds a [[Checkpoint Ring|Middle Ring]].

Eventually through the maze, the player finds a Warp Pipe going upwards; Once the player go through the Warp Pipe, they have to choose one of the two ways to go, a door and another Warp Pipe. The door is out of reach so the player needs to bounce on a [[Zeus Guy]]. After going through there, they are able to throw an Egg to break a rock on the ceiling, causing an [[arrow wheel|spinning wheel]] to fall down, allowing them to bounce up to a platform with hidden coins. Then, the player goes back down, and through the Warp Pipe.

Through it, there is another Middle Ring. After crossing some spikes, the player continue upwards, riding [[Flatbed Ferry|Flatbed Ferries]], until the player winds up in another maze of bridges. Through that, the player finds some rocks they need to throw eggs at to break, and after breaking them, the player can go through a Warp Pipe. The player then winds up at the end of the level.

However, the player can get a key, somewhere else through the maze, and ride a spinning wheel to get up to a locked door. Upon entering that locked door, the player finds a Middle Ring. The player then needs to cross a long gap of [[thorn]]s. After that, the player goes down a long shaft, at the bottom, they need to cross a pit of spikes. After crossing it, they find a few ways to go, with one of them being a door that takes the player back to the maze area. Instead, the player must ride a spinning wheel upwards, and across a pit of spikes, in order to reach an area where they can [[Ground Pound]] a breakable rock, and get to a door.

Upon entering the door, they find a [[! Switch]]. The player can hit it to make [[! Block]]s appear so they can cross a pit of lava. After crossing the pit, they get to a door, that takes them back to the shaft they went down earlier. If the player keeps going this way, they are stuck in an endless circle, so the only reason to go around that way is to get extra points and items.
{{br}}

==Enemies==
<gallery>
SMA3-Fang.png|[[Fang]]
SMA3-LavaDrop.png|[[Lava Drop]] (vertical)
SMA3-GreenGlove.png|[[Green Glove]]
Green Toady SMA3.png|[[Toady|Green Toady]]
GrimLeecher SMW2.png|[[Grim Leecher]]
YI-ZeusGuy.png|[[Zeus Guy]]
SMA3 Fooly Flower sprite.png|[[Fooly Flower|Dizzy Dandy]]
SMA3 Thorn.png|[[Thorn]]
SMA3-RedKoopaTroopa.png|[[Koopa Troopa]] (red)
SMA3-CoinBandit.png|[[Bandit|Coin Bandit]]
SMA3-Bandit.png|[[Bandit]]
SMA3-Grunt.png|[[Grunt (Yoshi's Island series)|Grunt]] (walking)
SMA3-FlyGuy.png|[[Fly Guy]]
</gallery>

==Helpers==
<gallery>
SMA3-MuddyBuddy.png|[[Muddy Buddy]]
</gallery>

==Gallery==
<gallery>
SMA3-MysteryOfTheCastle-Icon.png|Level icon from ''Yoshi's Island: Super Mario Advance 3''
</gallery>

==Names in other languages==
{{foreign names
|Jap=おしろのなぞ？おうようへん
|JapR=Oshiro no Nazo? Ōyōhen
|JapM=The Castle's Riddle? Practical Assessment (「応用編」 ''ōyōhen'' are problems that must be solved using the application of previously learned skills, such as review questions in textbooks)
|Chi=堡壘中的祕密<br>堡垒中的秘密
|ChiR=Bǎolěi zhōng de mìmì
|ChiM=Secrets inside the Fortress
|Spa={{nowrap|El misterio del castillo laberinto}}
|SpaM=The Mystery of the Labyrinth Castle
|Ita=Il castello labirinto
|ItaM=The labirynth castle
|Ger=Schloss Türenterror
|GerM=Door Terror Castle
|Fre=Mystère piquant.
|FreM=Complex mystery.}}
{{YI levels}}
[[Category:Castles]]
[[Category:Secret levels]]
[[Category:Yoshi's Island: Super Mario Advance 3 levels]]