Sonic finds himself having to travel through Hell after his friends disappear. The journey isn't easy as there are demons in the way.
Development started in 2018 and the final build was released on January 30th, 2023.
Tropes:
- Adaptational Villainy: Rouge, Tikal, and Honey, while allies to Sonic canonically, are demons out to kill him in this game.
- Amazing Technicolor Battlefield: In stark contrast to the rest of the game, the final boss's second form is fought in a dark void with rotating energy that is constantly changing colour.
- Call-Forward:
- The final boss's first form is a red serpent, much like the Egg Viper and mainly uses laser beams.
- The final boss's second phase takes place in a 3D space and is structured similarly to the 3DS version of the Time Eater, even using one of their attacks where they detach their hands to crush Sonic.
- Much like Alf Layla wa-Layla, Perfect Dark Gaia and Nega Mother Wisp, the final boss's second form has an attack similar to Darkness Slash where it slashes with it's claws and leaves an energy trail behind.
- Deal with the Devil: Eggman made an arrangement with Satan in order to capture Sonic's friends and rule the world here. As a result, Dr Eggman gains Satan's powers, his army and becomes ruler of Hell.
- Everyone Has Standards: Despite being the Prince of Darkness, even Satan is disgusted with Dr Eggman's lack of dignity after being defeated by Sonic.???: I gave you everything. My army, my power... and yet you still failed. You're pathetic.Eggman: Oh god, no! Give me another chance!
- The Death of Death: Death is the one who let Sonic into Hell and is eventually fought as a boss.
- Greater-Scope Villain: The Devil himself is never encountered at all, but he is the one responsible for Eggman gaining his powers in the game.
- Ludicrous Gibs: When Sonic dies, he explodes into a bunch of bones.
- My Name Is ???: After the final battle, Satan is referred to as ??? in the very little dialogue he has after Dr Eggman's defeat.
- One-Winged Angel:
- There are two parts to Death's fight. The second part has him grow much bigger.
- Shaft's Mecha Sonic form, after the first phase is beaten, takes on a fiery second phase. Beat this phase, and Shaft then becomes a Clipped-Wing Angel.
- Thanks to the powers of the Devil, Dr Eggman's machine takes on a demonic form for the final battle after Sonic deals enough damage.
- Title Theme Drop: In true Sonic fashion, the game's main theme gets remixed for the final boss fight.
- Token Good Teammate:
- Gloamgozer, unlike the other demons wanting Sonic in hell to kill him, actually attempts to keep him out and even warns him ahead of time of how dangerous the place where Sonic is heading is. He also argues with Death over letting Sonic in.
- Shaft, unlike his original depiction in Castlevania: Rondo of Blood and Symphony of the Night, is surprisingly honorable, to the point of expressing some level of regret over actually having to fight Sonic due to being sworn to do so, whereas his original incarnation is unrepentantly evil.
- Unexpected Gameplay Change: The final battle with Eggman has you fight in an overhead falling style as opposed to the rest of the game which plays like a regular Sonic game.
- The Voice: Satan is the one backing Eggman in this outing and while we do get dialog, we never actually see his face aside from the background during the first part of the final boss.
- You Have Failed Me: The moment Eggman is beaten by Sonic, the Devil essentially tells Eggman this as he collects with Eggman begging for another chance. Fortunately for Eggman, it's implied that the Devil just kicks him out of Hell rather than collect his soul.
