Roy's Castle is the fifth castle of Super Mario World.
The player starts in a room where there is lava on the floor, there is a Snake Block that will move the player past the lava and the spike room. The player needs to be careful though, because Lava Bubbles and Fireballs can damage the player and even lose a life if they don't have a power-up. Once the player is in the spike room, spikes will fall and the player can fall onto the spikes if they are not careful. Once they are out of the spike room, they will be in a room with lava (but there is a bridge) with Lava Bubbles, fireballs and Bowser Statues. The player has to avoid the hazards and get to the boss door.
The battle with start with two pillars crashing down so that the player cannot escape from the battle. Then Roy Koopa will move towards the left wall and climb up it. When he's on the ceiling, he will fall down when the player gets close. If he is stomped on, the walls will move closer (but will not collide). There are two ways to defeat Roy Koopa. One way is to simply just stomp on him three times. Another way is to throw two fireballs at Roy Koopa and stomp on him once. Both ways will defeat him. Mario will then have rescue one of Yoshi's friends, then they will move onto the next world, Chocolate Island.