Reset upon seeing the 'Sunset Hill' header and switch to S+TДЇollow the hub path, clearing Act 1, getting the hub chao, then clearing Act 3.ДЄfter clearing Act 3, reset after the whiteout (the game saves unlocking Knuckles). In Act 3, both possible key locations are on your path after the last chao, noted as yellow circles.Д¬oming out of Act 3, follow this route to go through Act 2, 1, and the special spring.Д¬oming out of the special stage, tag in the air to the right, then hold left so you ascend past the act 2 ring and a few ledges. Yellow circles = potential key locations after the last chaoДЇollowing this route, grab the pulley, tag to the chao, then fall and tag to act 3. All individual act maps taken from thesoniccenter be able to get the special key regardless of which set is chosen), but there are exceptions, and those will be pointed out. The route is designed to be as consistent as possible without revisiting stages (i.e. Every stage has two sets of special key locations (note the plural), and the game chooses one randomly upon entering the stage.

After you get your 10th chao, the special key is unlocked. To unlock Knuckles, Amy, and Cream, you have to beat Act 3 of Sunset Hill, Toy Kingdom, and Cyber Track (respectively) with Sonic as the lead character. This guide has an in-depth guide for the current 100% route which includes a map of each area and hub, the general route to take, and the reasoning behind each route decision.

Sonic advance 3 chaos angel