Sonic 3D Blast

Cheat mode:
Hold C and press Start at the title screen. The phrase "Press Start" will stop blinking to confirm correct code entry. Pause game play and press one of the following buttons to enable the corresponding cheat:

A: Skip to the next Act
B: Skip to the next Stage
C: Skip to the final Boss
X: One additional life
Y: Gain one medal (one continue is earned for every ten medals)
Z: Gain one Chaos Emerald (seven are needed for the best ending)

Note: The medal cheat may only be used nine consecutive times. The tenth medal must be earned in normal game play. After this is accomplished, nine more medals may be acquired through the cheat.

Alternate ending:
Usually the game ends with the final Boss escaping after his defeat in the seventh zone of Act 3. If you acquire all seven Chaos Emeralds you will be teleported to the final Boss fight area.
Information in this section was contributed by cassensjim.

Hint: Easy Lives in Green Grove and Rusty Ruins:
In Green Grove Zone Act 1, collect all the rings. Then, when you move onto Act 2, collect 200 Rings and go through the hidden passageway before the third part of the stage. Collect the extra life, and complete part three. Then, when you go to Rusty Ruins, go through the little hole. SpinDash, and get an extra life. You should have your maximum of 10 lives.
Information in this section was contributed by SonicD3.

Hint: Tails and Knuckles in Rusty Ruins Act 2:
When you get to the third part, immediate before the X Mark, go off the nearby cliff. Then, go down where the Bumblebee Badnik is located. Destroy that little object with the grass under it. Then, you can get to Tails. On the first part, go to where the Blue Shield is located, next to the first exit. Collect 50 Power Rings, then Spindash into that wall that looks pushed back slightly. If you won all the Special Stages so far, with six Emeralds you will get the Last Chaos Emerald.
Information in this section was contributed by SonicD3.

Hint: Staying safe on spikes:
To stay safe on the spikes, such as the Spring Stadium, keep jumping. Every time you jump the spikes will retract, leaving safe ground to land then. As soon as you do, jump again and repeat the process.
Information in this section was contributed by Travis Schwipps.