Sonic Unleashed is a game in the Sonic series. It is for the Wii, PS2, Xbox 360, and PS3. It was originally going to be called Sonic World Adventure. It is based around Sonic the Hedgehog running fast in the daytime, and being much stronger and slower at nighttime after transforming into a werewolf.
Sonic Unleashed starts off with Sonic confronting Dr. Eggman. They go into space, and Sonic defeats Eggman. He taunts him, and Dr. Eggman traps him and steals the Chaos Emeralds from him. His machine turns him into a werewolf, and he is hurtled into space. Dr. Eggman uses the Chaos Emeralds to split the Earth open and awaken the embodiment of evil, Dark Gaia. Sonic falls onto the ground. When he gets up, he finds a strange creature, passed out. The creature wakes up and can't remember anything. Sonic agrees to help him and stop Dr. Eggman's plans.
There are two main modes of gameplay in Sonic Unleashed. The first is 2D/ 3D platforming. It is the fastest Sonic has ever gotten. The normal Sonic levels are easier and shorter. The second mode of gameplay in Sonic Unleased is slower 3D platforming/ fighting. While the normal Sonic levels are about five minutes long, the werewolf levels are around ten minutes long. They are more fighting heavy, and there are several moments where the only way to advance in the level is to kill a hoard of enemies. Sonic can also go into Unleashed mode after killing several enemies. It makes Sonic faster and stronger temporarily.
Sonic Unleashed was made to have a lot less characters than games like Sonic '06. It doesn't have very many major characters. The main characters are Sonic the Hedgehog, Miles 'Tails' Prowler, Light Gaia (Chip), Dark Gaia, Professor Pickle, Orbot, and Dr. Eggman. There are also several bosses that Sonic fights.