"Sonic Adventure 2" is a platform video game developed by Sega and released in 2001 for the Sega Dreamcast. The game features two main storylines: one follows Sonic the Hedgehog and his friends, while the other focuses on Shadow the Hedgehog and Dr. Eggman. Players can choose between the Hero and Dark sides, each with unique characters and missions. The gameplay includes fast-paced platforming, treasure hunting, and mech shooting. Players can collect rings, defeat enemies, and complete levels to progress through the story. The game is known for its vibrant graphics, engaging soundtrack, and the introduction of Chao, small creatures that players can raise and train.