Hang Castle is a large, mysterious and spooky area filled with many towers under a large moon in the background. The stone hallways outside of the towers are filled with torches, and sometimes contain dull-colored plants to the sides. Some tall, round platforms contain notable illumination marks on the surface resembling spiders. Throughout the level, the castle seems to have red banners with an eye embedded on them. Mist seems to also be present in some parts of the stage. Towards the end of the level, there is a large tower crafted in the image of Dr. Eggman on one side and Neo Metal Sonic on the other.
After the second team battle, Team Sonic infiltrates the castle to find Eggman and Shadow. Team Dark enters the castle while Shadow ponders over his identity and what exactly Sonic is. Team Rose finds the haunted castle and continues after Amy reminds Cream and Big of Chocola and Froggy. Team Chaotix is off to find the keys located in the castle (presumably to get into Mystic Mansion). Following Mystic Mansion, the next stage, the teams all pass through the Hang Castle area again to fight Robot Storm before moving on to Egg Fleet.
Hang Castle is the first of two stages that contain the mysterious orb switch (the other stage being Mystic Mansion) which seemingly flips the stage upside down. The player must tread around the floating platforms cautiously, especially if they are used to carry the player across bottomless pits. Some of the floating platforms that move up and down will not move until the player stands on them.
Because of their unique Light Dash ability, Team Sonic and Team Dark can find long trails of rings in this level. Also as Team Sonic and Team Dark, they will need to run vertically down along the surface of a tall tower, avoiding obstacles and gaining points via Rainbow Rings in the process. The player cannot backtrack in this section.
The stage introduces stone walls that can be destroyed with Power Formation attacks which conceal Item Boxes, switches or passageways necessary for the player to proceed. Also new to this stage are the torches which can be used to score points by extinguishing the flames, though if the flame is touched, the player will take damage. Some torches are simply flames formed on platforms and in midair, though with the latter they serve to create some sort of an invisible pathway the player can walk on.
Collect the keys without being detected by the enemies!
If the Eggman statue is looked at while upside down, a statue of Neo Metal Sonic can be seen, foreshadowing that Eggman is not the real villain after all. (This is seen only in Team Sonic, Team Dark, Team Chaotix and Super Hard Mode versions)
This is the only stage in Sonic Heroes to have two musical tracks: one for when the castle is right-side up, and another one for when it's upside down.
If Team Sonic and Team Dark are played and start at the beginning of the level, if the player pauses at the gap at the beginning, the buildings are shown to be stretched and falling is shown to be a never-ending void if somewhat hacked.
Hacking reveals the orb switches don't actually invert the level, but warp the characters to a different part of the level made to appear upside-down.
If Team Sonic and Team Dark are played during this level and reach the end, the player can see that the moon has a face with a creepy smile while going towards the roof of the castle.
The moon that looms large over the stage is actually that of Earth's moon and Jupiter's moon Ganymede fused together. This gives it the creepy face-like lunar maria.