Change Views in Special Stage
When you're about to get a Chaos Emarald, press X to "freeze" the view. For example, if you freeze the view while the view is above Sonic, you'll see Sonic grab the Chaos Emerald from that viewpoint.
To view the emerald from below, hold Z as you approach it.
At the title screen hold C and press Start. To use the codes, pause the game while playing and press any of the following keys:
A Skip to next Act
B Skip to next Stage
C Skip to the final boss
X Gain 1 life
Y Gain 1 medal (10 medals = 1 continue)
Z Gain all Chaos Emeralds
Note: You must earn every 10th medal. That is, you can gain 9 medals with the cheat code, earn 1, gain 9 more, etc.
Extra Life in Diamond Dust
To find the extra life icon at Diamond Dust, go across the icy river at the beginning of the level to the ice sickles. With a Sonic Spin break through the ice and duck down the hidden tunnel!
Extra Life in the Rusty Ruins
At the very begining of Rusty Ruins, there is a door behind you. Go back to that door and do the spin attack to open it. Inside you'll find an extra life.