For extra points, pass any zone in a certain amount of time. For the best bonus, enter the Debug Mode code. The clock will freeze and you'll always score a 50,000 bonus!
While the demo is playing, hold A + B + C. Sonic will get confused, lose his place, and possibly die.
At the title screen, press Up, C, Down, C, Left, C, Right. While playing, you can pause the game and use A to restart, B for slow motion, and C for frame advance.
Enable Control Mode. After pressing Start to begin a game, hold A until you see Sonic. If you see a bunch of hex numbers on the top of the screen, you're in Debug Mode.
To start debugging, press B, then you can select any sprite in that level and put it on the screen. To select a different sprite, press A, and to place it on the screen, press C. Note that sprite selection is different from Zone to Zone. Also, instead of displaying the time elapsed, it displays the number of sprites currently on the screen. Control Mode functions work as well.
Note: This only works on the first production releases of Sonic.
In Green Hill Zone - Act 3, there is a 1-Up at the very bottom of the level. Collect it along with enough rings to make 100 for a second life. Next, grab the 1-Up at the top of the loop-de-loop and die. Repeat until you have enough lives.
Get all Emeralds
This cheat allows you to start at the First Level with all the Emeralds, and with lots of Continues. Use the Level Select cheat (see above) to get to the Special Zone. When you get the Emerald, and have entered into the First Zone, press Reset.
Use the Level Select cheat to get to the Special Zone again. When you get the next Emerald, and have entered the First Zone, press Reset again.
When you have all the Emeralds, continue on with the
first level. You get to keep the Emeralds and the
Continues accumulated so far.
At the title screen, hold A then press Up, Down, Left, Right. When you hear the chime, press Start.
If that doesn't work, try this: at the title screen, press Up, Down, Left, Right, hold A, and press Start. After doing this once, you only need to hold Start + A to enter the level select.
Marble Zone Shortcut
In Marble Zone act 3 you will find three chandeliers with spikes in them. Go to the far wall (on the right) and jump to the right to find some goodies. Now jump through the wall on the right again, but be careful of the other chandelier.
Scrap Brain Teleport
On the last level (Scrap Brain), find the ledges that move right then left. Go to the left side of the wall and wait for the platform to move. As soon as it starts to move left, duck. You'll go through the wall. While here, press Left to teleport right and Right to teleport to the left.