Sonic Gems Collection

At the Sonic CD title screen while "Press Start" is blinking, press Down(3), Left, Right, X to display the sound test menu. Set one of the following sound combinations and press Start to activate the corresponding cheat function:

Sounds Result
PM11, DA09 View hidden scene
PM04, DA21 View hidden scene
PM07, DA07 View hidden scene
PM12, DA25 View hidden scene
PM12, DA11 View hidden scene
PM03, DA01 View hidden scene

Successfully complete the game, then restart the game in "Time Attack" mode. The following options will be available if the "Time Attack" game can be completed within the corresponding time limit.

Successfully complete Sonic R with all characters, including bonus characters. Then, go to the Sonic R title screen and use the Analog-stick to move the "R". Press Triangle to change the color of the "R".

Finish in first place on the Radiant Emerald course to unlock Dr. Robotnik. Alternately, successfully complete all levels.

Collect all five coins in Radioactive Factory, and finish in first, second, or third place. Then, defeat Mecha Knuckles in a race to unlock him.

Get the five Sonic coins in one of the following levels to play as the robot form for the indicated character:

Sonic R: Mecha Knuckles: Reactive Factory
Mecha Robotnik: Any level with Robotnik
Mecha Sonic: Resort Island
Puppet Tails: Radical City

Collect all seven Chaos Emeralds from the first four courses. To collect a Chaos Emerald, you must collect it and finish in first place in that race. Then, press Down while highlighting Sonic at the character selection screen.

After completing the game with any character, hold Square or Circle and press Start to skip the credits.

Enter the options menu and select the "SFX" option. Play sounds 0, 4, 2, 5, 5, 7 (in order). If you entered the code correctly, the screen will shake. While playing the game, press X + Square + Start to enable the code.

At the Sega logo, press Up or Down to access time attack and sound test options.