Special Stage (Sonic Advance 2)

Special Stages in Sonic Advance 2 are a series of special levels. Unlike the previous Sonic games, these special stages have many unique features in terms of gameplay and when successfully cleared, the player is rewarded a Chaos Emerald. As the Chaos Emeralds are not shared (unlike Sonic Advance), each character is required to collect the 7 Emeralds seperately. If Sonic collects the 7 Chaos Emeralds, he will be able to progress into the game's true final/extra zone. If any character collects the 7 Chaos Emeralds (including Sonic), the game's Tiny Chao Garden mode and Boss Battles in Time Attack become available to the player. If all the characters have all 7 Chaos Emeralds each, Amy Rose becomes a playable character.
 * For Special Stages in general, see here. 

Gameplay
For a character to enter a Special Stage is admittedly one of the most difficult requirements in the history of Sonic games. The player must find 7 Special Rings hidden throughout an act and must finish the stage without losing a life. Because such objects are difficult to locate, it is deemed impossible for inexperienced players to find all 7 Special Rings of an act without the help of a game guide.

Once the player successfully reaches into the Special Stage, the player will need to control the character around a large, rectangular, 3D enivronmental stage and their main objective is to collect 300 Rings within 2 minutes. However, there won't be 300 Rings physically on the stage so the player should collect Rings in succession; collecting Rings in succession will raise the ring multiplier to x2 (meaning that 1 physical ring is worth 2 actual rings) and as long as Rings are collected in succession the ring multiplier will continue to increase until it reaches x9. There are gimmicks such as a dash panel and a spring which can accelerate the character or launch him/her up into the air respectively. The only obstacle is one of Eggman's robots from Sonic Adventure: E-100 Alpha who constantly chases the character. Touching it will damage the character, making him or her lose some Rings. If it touches the character while having no Rings, the special stage ends in a failure. E-100 Alpha is indestructible but if contacted by a Spin Jump from the character, the robot will temporarily be knocked down. The arrow next to the character will indicate the direction of where E-100 Alpha is. (Green means far distance, yellow means fairly short distance and red means very short distance.)

When having 30 seconds left on the timer, the music will change and the timer will flash red indicating that the player doesn't have much time on the Special Stage to pass the objective. When having 300 Rings, a figure of an Emerald flashing green, red and blue will appear indicating that the player has passed the objective in the Ring Count.