Castle Siege is a stage in the Wii videogame Super Smash Bros. Brawl. It is meant to represent the Fire Emblem series as a whole, rather than one game in particular. Castle Siege is Ike and Marth's home stage. It takes place on the roof of a Castle, which is being attacked, hence the name Castle Siege. The stages' main platform is rather curvy, and it has a few extra platforms suspended in mid-air. However, after a certain time passes, the roof will collapse, and the players will fall into the Castle's throne room. This is set on a smaller area, comparable to Flat Zone from Super Smash Bros. Melee. It has a few platforms, held up by statues, that can be destroyed. This results in the platforms falling, thus less places to run. After a certain time passes, the floor of the throne room yet again gives way and the players fall into the underground. The underground is a dark lava filled stage, not unlike Norfair.
Castle Siege is the first Fire Emblem stage in the Super Smash Bros. Series, as Super Smash Bros. Melee didn't have a stage representing Fire Emblem. Instead, in Melee, the special events that starred Marth or Roy took place on the Zelda themed Temple stage. This particular stage also featured music from Fire Emblem if the player pressed and held down the R button while selecting the stage.