• In Sonic Adventure 2: Shadow is introduced as the ultimate life form, created by Professor Gerald Robotnik, Dr. Eggman's grandfather, as part of Project Shadow. The aim was to achieve immortality and cure Gerald's granddaughter Maria's illness. Shadow's initial appearance is as an antagonist, driven by a false memory to seek revenge against humanity. However, he ultimately becomes an ally after his true memories are restored by Amy Rose.
• In Sonic the Hedgehog 3: While Shadow's creation is still tied to Gerald Robotnik, the movie simplifies his backstory for a quicker narrative pace. Shadow arrives on Earth via a meteorite, and his motivations are adjusted to align with the movie's plot, focusing on revenge but with Sonic playing a more pivotal role in his redemption. Notably, Amy Rose does not appear in the main story, thus her role in Shadow's transformation is absent, with Sonic taking on that responsibility.

The Presence of Rouge the Bat

• In Sonic Adventure 2: Rouge plays a significant role as a jewel thief who works with Eggman and Shadow. Her character adds complexity to the narrative with her treasure-hunting escapades and her uneasy alliance with Eggman and Shadow.
• In Sonic the Hedgehog 3: Rouge does not appear in the main narrative, though elements of her story, like the heist scene, are present but adapted to fit the characters who are in the movie. This absence changes the dynamics of the team and the plot's progression.

Gerald Robotnik's Fate

• In Sonic Adventure 2: Gerald is executed after his descent into madness following Maria's death, which sets off the events leading to the ARK's potential destruction.
• In Sonic the Hedgehog 3: Gerald is killed in an anticlimactic fight with Eggman inside the Eclipse Cannon space station, altering the emotional and narrative impact of his death compared to the game's more tragic depiction.

Character Dynamics and Introductions

• In Sonic Adventure 2: The story is split into Hero and Dark campaigns, giving equal focus to both Sonic's and Eggman's teams. Characters like Amy Rose and Big the Cat have significant roles, with Amy particularly instrumental in Shadow's character arc.
• In Sonic the Hedgehog 3: The focus is more on Sonic, Tails, and Knuckles with Shadow as the central antagonist. Amy Rose only appears in a post-credits scene, which significantly alters the character interactions and plot development seen in the game.

Thematic Elements and Tone

• In Sonic Adventure 2: The game delves into darker themes like betrayal, redemption, and the consequences of scientific hubris. It's marked by a more serious tone, especially in Shadow's narrative.
• In Sonic the Hedgehog 3: While it adopts the darker tone from Sonic Adventure 2, the movie balances this with the humor and light-heartedness that has characterized the film series, sometimes leading to less intense moments than in the game. This includes "corny dance breaks and cheesy one-liners", which add a unique flavor to the movie's adaptation.

Conclusion