World 2-Castle (New Super Mario Bros. Wii)

 is the castle and last level of World 2 in New Super Mario Bros. Wii. The boss battle in this level is against Roy Koopa.

Layout
This is an autoscrolling castle level filled with lava pits, and three-way corridors, of which only one is the correct path, much like in Super Mario Bros. and Super Mario Bros.: The Lost Levels. If the correct path is taken, a chime indicating so sounds and the player will go to the next part; if it is incorrect, a buzzer sounds and the player will have to repeat the same area all over again. In order to complete that area quickly, the player needs to take the upper route, the lower route, and the center route in that exact order. Lava Bubbles are also common in this castle. If Mario or any of the other players stay too long between a wall and the edge of the screen, the autoscrolling level squishes them, instantly killing them and causing them to lose a life.

Roy Koopa is fought here for the second time. He attacks by popping out of pipes that Magikoopa produces with his magic before the start of the battle. When Roy jumps out of a pipe, he causes a tremor upon landing, which temporarily stuns any players on the ground. Mario also needs to avoid getting squished by Roy. Roy is defeated after getting hit three times. Upon his defeat, the player gets the key to unlock World 3.

Star Coins

 * Star Coin 1: The first Star Coin is floating above Mario and co. at the very start of the level. There are two ways to obtain it. Firstly, Mario and co. can get on top of the nearby ? Block and jump from it to the Star Coin, or they should take the middle path to be led to it instead (the former is quicker, the latter is easier).
 * Star Coin 2: At least a Super Mushroom is required for this one. To the right of the red Warp Pipe-emerging Piranha Plant is the second Star Coin floating high up between two walls, and it is blocked off by many Brick Blocks. Mario and co. should destroy enough Brick Blocks to jump up or wall kick to the Star Coin.
 * Star Coin 3: The third Star Coin floats just over the lava in the area with several Coins, Brick Blocks, and Dry Bones. Mario and co. should activate the nearby P Switch, and quickly grab the Star Coin over the new platform of Brick Blocks before the P Switch's effects wear off.