Exception is the true final level in Sonic Rush. It is accessible at the character select screen after collecting all the Sol Emeralds with Blaze and the Chaos Emeralds with Sonic. It opens with a cutscene in which Dr. Eggman and Eggman Nega explain the awesome reaction power when the Chaos and Sol Emeralds are brought together and as a result, Sonic and Blaze's worlds are merging together, which both Eggmen hope to build their Eggman Empire in. In other words, Exception is the large, oddly-colored dimensional rift that is the result of Sonic's world and Blaze's world merging together into one.
For this battle, Sonic and Blaze use the power of the Chaos and Sol Emeralds to transform into Super Sonic and Burning Blaze respectively. The player takes turns in controlling one character at a time. Sonic battles Eggman on the top screen in the Egg Salamander, a machine that looks similar to one used in the final level of Sonic Advance 2. The Salamander's attacks are similar to that final battle, and it starts with shooting a barrage of green shots at Sonic. Those green shots will first move horizontally, then vertically. Super Sonic must deflect these back at Eggman by boosting, however, this is only possible when the shots are moving horizontally. Another type of attack is to fire moving blue darts which shoot rotating lasers at Sonic. Boosting onto them may also result in damaging Eggman. Eggman will sometimes fire homing rockets continuously, you have to dodge them quickly.
Once enough hits are landed, the Eggmen take to the bottom screen where Eggman Nega takes control and battles Burning Blaze, who can attack with fire balls. In this form their machine is known as the Egg Salamander Nega. This second machine becomes stronger, it could create voids and scratch Blaze with its hands, therefore hurting her by seizing Rings. These attacks are more powerful, although counterattack by players are easier to perform. The villains will return to the top screen after a number of hits, and back again. After the second time to switch to Blaze VS Eggman Nega, the boss will become faster and more difficult to defeat. This pattern repeats until the boss is defeated, and Sonic and Blaze return to their respective worlds.