Mirage Saloon is based off of Dust Hill, a zone planned for Sonic 2 that was ultimately scrapped. The desert setting is inspired by the American Old West, complete with cacti, bars, revolvers, and wanted posters. Fang the Sniper from Sonic Triple Trouble, as well as Bean the Dynamite and Bark the Polar Bear from Sonic the Fighters, make appearances during the second act's boss fight. For the achievement/trophy of this zone, you must find a hidden room in the second act.
Act 1[edit]
Depending on the character you play, the first act can look very different. Sonic and Tails ride along the Tornado, Tails' biplane, in an auto-scrolling stage, with the exception of some travel across a train on foot. Simply avoid the enemies on the way to the boss, the Uber Caterkiller. To defeat it, hit its head with a Spin Attack six times; this is easiest when the Caterkiller jumps from the side of the screen, rather than from the front or back.
As Knuckles is knocked off the Tornado at the start of the zone, his version of the act takes place on the ground. Proceed through it like you would any other stage until you reach the Dangerous Ball Tower (as seen in Sonic Chaos), which tosses the spiked parts of its body at you. Avoid these hazards until the tower gets low enough and then use a Spin Attack to hit its head. It will then rebuild its body and the cycle will repeat. Like the Uber Caterkiller, you must get six hits in to defeat it.
Act 2[edit]
To find the hidden room, proceed through the zone as usual until you come across a bar (if you're traveling too high, you won't be able to spot it, as it can be found indoors). To the right of the stools and the bar itself is a large barrel. Walk into the barrel to push it and you'll drop down onto a sprinkler. Run onto the water it produces, right into a giant ring. This secret should come in handy if you still haven't obtained all seven Chaos Emeralds. As for the rest of the act, you may come across pinball flippers, piano keys, and barrels that turn over if you stand on them. There are also some star-shaped balloons you can bounce around on in the air, though keeping the high ground here isn't necessary. Stand on a barrel that turns over to confront the boss, one of the Hard-Boiled Heavies.
The Heavy Magician can change form to resemble some of Sonic's former adversaries: Fang, Bean, and Bark. As Fang, the Magician will shoot corks from its gun; as Bean, the Magician will throw bombs; as Bark, the Magician will pound the ground, causing debris to crash down on you from above. Hit the Magician in any one of these forms and it will revert back to its original form, allowing you to attack it. Get eight hits in on the Magician when in its original form to defeat it.