Sonic Rush

Sonic Rush is a 2D platform game, similar to earlier games in the series like Sonic Advance as well as later ones like Sonic Mania. The player controls either Sonic the Hedgehog or Blaze the Cat, who differ in terms of special abilities. In the tradition of past Sonic games, gameplay consists of moving quickly through levels, collecting rings and defeating enemies. The player collects rings as a form of health; when they are hit by an enemy or harmful obstacle, their rings bounce in all directions and can be recollected.

The player begins the game with three lives, one of which is lost when the character is hit without any rings in their possession, crushed, drowns, falls into a bottomless pit, or reaches the act's 10-minute limit; losing all lives results in a game over. Both of the DS's screens are used to display the play area, with the player's character moving between them as necessary. Levels in the game are divided into "zones", each consisting of two acts of normal gameplay then a 3D boss battle. The course of the game differs depending on whether Sonic or Blaze is chosen; the seven zones are the same, but are accessed in different orders.

Blaze the Cat is somehow pulled from her native dimension into Sonic's world. Her world had seven Sol Emeralds—similar to the Chaos Emeralds—but they were stolen by Doctor Eggman. She then makes it her goal to retrieve them. While searching, she meets Cream the Rabbit and is surprised by her politeness. Meanwhile, Sonic is searching for the Chaos Emeralds, which have been stolen by Doctor Eggman Nega, Eggman's alternate counterpart from Blaze's dimension.

Sonic briefly encounters Blaze during his search, but she departs before he can question her. His friend Tails learns that the two dimensions are merging somehow, and both will collapse if the process is not stopped. Suspicious of Blaze, Sonic and Tails begin searching for her. Upon finding Blaze and Cream, Sonic questions Blaze about her nature, but she refuses to give any information and leaves with Cream.

Sonic Rush was developed by Sonic Team and Dimps, and published by Sega. Yuji Naka, Sega's executive managing director, announced the game at Electronic Entertainment Expo (E3) 2004, along with Project Rub. A demo of the newly titled Sonic Rush was featured at E3 2005, and won video game publication IGN's "Biggest Surprise" award. Blaze the Cat, a new character, was revealed at Tokyo Game Show (TGS) 2005.

5D format was based on Sonic Team's idea to combine elements from 2D and 3D games in the series. Director Akinori Nishiyama stated in a September 2005 interview with GameSpot that Sonic Team "wanted to keep the elements from 2D, yet still explore some of the new elements from 3D." At TGS 2005, he stated that while working on Sonic Advance 3, he realized that the series was becoming more complicated, opting for a "fast, dynamic action" approach to the next title in the series.

Sonic Rush was released on November 15, 2005, in North America; November 18 in Europe; and November 23 in Japan. It was the ninth best-selling DS game of December 2006. It sold 360,000 copies in Europe from March 2006 to March 2007. The game received a "Platinum" sales award from the Entertainment and Leisure Software Publishers Association (ELSPA), indicating sales of at least 300,000 copies in the United Kingdom.

The game was released to "generally favorable" reviews, according to video game review aggregator Metacritic. Critics praised the game for its usage of elements from older Sonic games. GameSpot, IGN, and Nintendo Power compared the game to older games in the series, specifically those on the Sega Genesis. GameSpy staff writer Greg Sewart offered a similar opinion, also praising the game for its "gorgeous graphics".