Donut Secret House

Donut Secret House is a secret Ghost House in the game Super Mario World. It can be accessed by completing the secret exit of Donut Secret 1. This level also has a secret exit. This level is the home of the Big Boo, the boss who protects the Star Road. If the Mario Bros. beat this boss, they will have access to the Star World. This is the only level other than a castle or a fortress to feature a boss battle.

Overview
Donut Secret House is one of two Ghost Houses in Donut Plains. This level consists of two main rooms, a boss room, and a hallway used to reset the second room. There is a 400 second Time Limit to clear the level. It contains no Dragon Coins in the original SNES version.

In the first room, the player will have to navigate their way past Circling Boo Buddies. After the Boo Buddies, the player will encounter a single Eerie and a Big Boo. If the player activates the Switch Block, the Empty Block will turn into a coin, and the Jumping Board that was on top of it will fall down, allowing the player to jump over the Big Boo easily. There is then a short series of staircases, under which is a platform that is inaccessible from this room. There is a single ? Block above the inaccessible platform containing a 1-Up Mushroom. The door at the top of the stairs leads the player to the second room.

Exits
After traversing the first room and entering the second room, the direction of travel is switched and there is another group of Boo Buddies. Just past that point is a small platform with five coins on it. In order to access the standard exit, these coins must first be collected, and then the Switch Block on the leftmost end of the room should be activated, revealing a Blue Door on said platform. If the coins are not collected, the player will not be able to access the Blue Door as it will be surrounded by empty blocks during the duration of the Switch Block activation.

In order to get to the secret exit, the player must still activate the Switch Block, revealing three ? Blocks in the floating arrangement of Rotating Blocks to the left of the Blue Door, making it possible to stand on what was previously empty space. The player needs to stand on the middle ? Block and hit the Rotating Block directly above. A Beanstalk will then appear, which must quickly be climbed to access a long platform, at the end of which is a another Blue Door. (The Switch Block must not have timed out in order for the door to still be there.) The door leads to the boss room with one Big Boo and two small Boos. The Big Boo must be defeated by throwing Grab Blocks at him. The boss is harmless to the player but the regular Boos are not. The player must be careful not to create a hole in the floor and fall through it. After the Big Boo is hit three times, he will be defeated, leading to Star World 1. This is the only level with a secret exit that is not accessed by either a keyhole or a Giant Gate.

Trivia

 * In the SNES Japanese version, the walls at the end of the two main rooms in the level are not extended to fill the whole screen.