Labyrinth of the Castle is the fourth and final Zone of Sonic Labyrinth. As with other Zones in this game, Labyrinth of the Castle consists of three standard Acts followed by a shorter fourth Act which contains a downhill slide and the Zone's boss.
Set within Dr. Eggman's spooky fortress, this level is significantly less forgiving than the previous three, with bottomless pits frequently awaiting after any mis-aimed Spin Dash. Projectile-lobbing Badniks perch on inaccessible slabs of terrain, and flaming arrows fly hither and thither across the long corridors. Watch for pounding guillotines and falling stalactites from above, and keep an eye open for will-o'-the-wisps and crawling flame caterpillars that roam aimlessly around the floor. Conveyor belts flow and cascade like waterfalls. The only way to navigate the stage is to traverse a series of labyrinthine doorways that warp to different parts of the board.
The second Act of this Zone features a giant clock placed above the goal, which the camera pans up to once the player finishes the stage. If the player collects all three keys and makes it to the goal before the clock goes below 2:00, the clock will ring three bells and release a flock of doves.
The starting time limits are as follows: 1:30 for the first Act; 2:30 for the second Act; 3:00 for the third Act. The Zone's boss is the Smiley Bomb.
|The castle corridors are filled with ghosts and guillotines, arrow-firing bird soldiers and treacherous traps. Watch your step on the narrow walkways - there are drops on each side, and it's a long way down.
— Sonic Labyrinth US manual
|Aroro — Birdlike bots that shoot arrows from a position Sonic cannot reach.
|Dragogo — Invincible dragon Badniks that pop out of the ground and shoot fireballs.
|Gaikoko — Ghostly skull bots that spout flame puffs.
|Kapupu — Fish robots that pop out from streams to bite Sonic.
|Nyororo — Snake robots that slither along the ground.
|Peroro — Tiny bots that roll along the ground that attack by licking Sonic.
|Robototo — Soldier-like robots that march forward.