World 4-Ghost House (New Super Mario Bros.)

 is the Ghost House of World 4.

Layout
To start, Mario should step onto a striped platform that takes him past a wall. The first Star Coin can be found by going up past the blocks and right to another striped platform where he will find the coin above it. After the platform, Mario should press the ! Switch and go through the door, avoiding the Balloon Boo along the way. To get the second Star Coin, Mario should press another Wall Jump on the first red blocks he sees (for the third Star Coin, see "Secret Exit") and go up. Then, the player needs to jump on the blocks, past the first door (if Mario goes through the first door, it will take him back to the start of the area), and into the second door. This will take Mario outside, to the Flagpole.

Secret Exit
To access the Secret Exit, the player needs to be Mini Mario. When Mario reaches the area with the second Star Coin, Mario should get onto the pipe, not entering it. Then, he should Wall Jump on the pipe, reaching a faraway door. By continuing to Wall Jump and by going up, Mario will reach the third Star Coin. Going through the door takes Mario to the Red Flagpole.

Star Coins

 * Star Coin 1 - Enter the door in the beginning of the level and hit the ? Switch. Four blocks attached with strings will drop from the ceiling. Hop on top of one of these and when it goes up, the player will be transported to the first Star Coin.
 * Star Coin 2 - Using some red blocks, Wall Jump off them to reach a higher area and where the Star Coin is found.
 * Star Coin 3 - Jump off the aformentioned pipe onto the above platform as Mini Mario or Luigi. Keep wall jumping until the player finally reaches the Star Coin.

Enemies

 * Boo
 * Balloon Boo