Sonic Heroes

Sonic Heroes is a 3D platformer. While the preceding Sonic Adventure games for the Dreamcast featured elements of action-adventure and exploration, Sonic Heroes focuses on linear platforming and action, similar to the Sonic the Hedgehog games for the Sega Genesis. The story is also simpler than those of the Sonic Adventure games. In it, series antagonist Doctor Eggman threatens to use a weapon to destroy the world and sends out legions of robots.

Four groups of three characters from the franchise's history separately team up to put a stop to Eggman's plans. The player navigates using one of the teams, who serve as the player characters. The teams include Team Sonic, which consists of series regulars Sonic the Hedgehog, Tails, and Knuckles the Echidna; Team Dark, which includes Shadow the Hedgehog and Rouge the Bat from Sonic Adventure 2, and new character E-123 Omega (considered a spiritual successor to E-102 Gamma from Sonic Adventure); Team Rose, which has Amy Rose, Cream the Rabbit and Cheese from Sonic Advance 2 (2002), and Big the Cat from Sonic Adventure; and Team Chaotix, consisting of Espio the Chameleon, Charmy Bee, and Vector the Crocodile from Knuckles' Chaotix (1995). Each team has its own campaign, called a story.

Sonic, Tails, and Knuckles receive a letter from Doctor Eggman, telling them that in three days, he will launch his Egg Fleet in an attempt to take over the world, challenging them to stop him. Rouge infiltrates one of Eggman's bases, where she is surprised to discover Shadow, last seen falling from the Space Colony ARK, asleep in a pod. When she awakens him and one of Eggman's robots, E-123 Omega, from their stasis, the three reluctantly agree to work together, with Omega wanting revenge for being locked up and Shadow, who has amnesia, wanting answers regarding who he is. Amy helps Big and Cream track down Big's pet, Froggy, and Cheese's brother, Chocola Chao, who were both reportedly kidnapped by Sonic. The Chaotix Detective Agency (Vector, Espio, and Charmy) receive a job offer from a mysterious client, where they execute a series of tasks to prove themselves.

The four teams chase down Eggman through various zones, crossing paths with each other at several points, until they all end up on the Egg Fleet. There, Rouge discovers an armada of Shadow Androids, wondering if their Shadow is just one of them too. The Chaotix end up rescuing their mystery client, revealed to be Eggman. He explains that he was locked up and betrayed by Metal Sonic, now going by "Neo Metal Sonic", who had adopted the guise of Eggman and taken control of the Egg Fleet to prove himself superior to Sonic.

Sonic Heroes was developed by the 19-member Sonic Team USA in San Francisco to commemorate the Sonic series' 12th anniversary. Development was led by producer Yuji Naka and director/lead designer Takashi Iizuka, and lasted 20 months. The majority of the development team had worked on previous Sonic games. Iizuka did not want to make a sequel to Sonic Adventure 2 (2001), as he worried it would only appeal to Sonic fans.

Interested in returning to gameplay similar to the Genesis games, Sonic Team decided to design Sonic Heroes so casual players not familiar with Sonic could adapt. Iizuka said the development period of Sonic Heroes was the most stressful of his career because of deadlines and Sega management. A fellow designer became ill, so he worked relentlessly, lost 22 pounds (10 kg), and suffered from insomnia. The deadline became so severe that programmers were ordered to only fix bugs that affected progression in the game.

Sonic Heroes received generally "mixed or average" reviews, according to the review aggregator website Metacritic. Some reviewers felt the game was better than the previous 3D Sonic games but still below the quality of the 2D games. The PS2 and PC's version's reviews were considerably worse than others; reviewers noted clipping, graphic faults, and its lower frame rate.

The aesthetics and sound were generally well received. IGN lauded detailed, varied, and realistic character models, and wrote that the textures were detailed and crisp. They also praised the realistic shading and lighting effects. Although GameSpot thought the graphics were not much of an improvement from previous games—comparing them to "a glorified Dreamcast game"—they still praised its steady frame rate, art design, and vibrant colors.

After Sonic Heroes, Sonic Team USA was renamed Sega Studios USA. Their next project was Shadow the Hedgehog (2005), a spinoff starring Shadow set shortly after the events of Sonic Heroes. In 2008, after working on a few more games, the division was merged with Sonic Team in Japan. In a 2017 series retrospective, USgamer ranked Sonic Heroes among the franchise's bottom half of games.

They wrote that the system of switching between characters was unwieldy and annoying, but still interesting because it made the game feel like a puzzle video game. They also praised the design of E-123 Omega.