Sega Genesis Collection - Sonic The Hedgehog Cheats and Hints (PSP)

In the game, Sonic has to prevent Doctor Robotnik from collecting six of the Chaos Emeralds in an attempt to rule South Island. He must traverse six "zones", each comprised of three stages or "acts", until he confronts Robotnik for the last time in the Final Zone. The gameplay centers around elements that exploit the increased performance of the 16-bit console over its 8-bit forebears. It is notable for being both simplistic and engaging for players.

At the time of its release, Sonic the Hedgehog was one of the fastest platformers that had yet been released. Sonic could run, jump and roll at significantly higher speeds than most platformers of the time. Unlike other platformers, the game's levels were designed to encourage the player to progress quickly. Springs, slopes, high falls and loop-de-loops were all available to both boost and challenge the player to reach high speeds. This was all accomplished without any slowdown in framerates, adding to the experience. (Wikipedia)

Cheats

Level select:
Press Up, Down, Left, Right at the title screen. A chime will confirm correct code entry. Hold A + Start to begin game play. In the Japanese version, press Up, Down(3), Left, Right at the title screen. Hold A + Start to begin game play.

All Chaos Emeralds:
Enable the "Level select" code. Select the "Bonus level" option on the level selection screen. Obtain the Chaos Emerald, reset the game, and repeat the process until all of them are in your possession. Allow the game to continue after obtaining the last Chaos Emerald to start in the Green Hill Zone.

Note: When you collect all of the Emeralds, you will not become Super Sonic, but you will be practically invincible. Try the following. When you have no rings, get attacked by something. Sonic will fall back (as if he had a shield on him), but he will not die. However, Sonic will die if he falls off of the edge of something, sinks underwater, etc.

Debug mode:
Press Up, C, Down, C, Left, C, Right, C, Start, then hold A at the title screen. Continue to hold A until game play begins. Screen coordinates will appear instead of a score and the number of objects displayed will appear instead of the time remaining. Use one of the following controller actions to enable the corresponding debug code. Note: This code may only be enabled on the first version of the game.

Object transformation
Press B during game play to change Sonic into a game object. Press A to change into a new object. Press C to place an object on the screen. Press B again to revert back to Sonic. Note: The type of object that may be selectable will vary from level to level.

Invincibility
Sonic is, by default, invincible in debug mode. Note: Sonic can still drown, be crushed, fall and die, etc. He is only invincible to enemy attacks.

Slow motion
Pause game play and hold B.
Restart
Pause game play and press A.
Frame advance
Pause game play and press C.

In the Japanese version, press press Up, C, Down, C, Down, C, Down, C, Left, C, Right at the title screen. A sound will confirm correct code entry. Pause game play, then press the buttons described above to activate slow motion, restart, and frame advance.

Crazy Sonic:
Hold A + B + C during demonstration mode for force Sonic to run into objects and act strangely. Note: This may also be done during the ending sequence after completing the Final Zone.

Bonus points:
Complete Green Hill Zone 1-1 or 1-2 in 29 seconds or less to receive 50,000 bonus points.

Unlimited lives:
Collect the extra life at the very bottom of Green Hill Zone - Act 3. Accumulate 100 rings to obtain another extra life. Collect a third extra life located at the top of the loop-the-loop. Intentionally lose a life and repeat the process.

Control ending sequence:
Enable the "Debug mode" code. Press B when Sonic is running with the animals at the end, then turn back into Sonic. You can nowcontrol yourself.
Information in this section was contributed by HOOHAZ.

Gameplay Hints

Defeating the first Boss:
Hit him before he gets out his wrecking ball. While he swings the ball, jump (but do not hold it down) and hit him. Keep doing this until he is defeated.

Special Zone entrance:
You can almost always have the Special Zone entrance open (the giant ring next to the sign at the end of level Acts 1 and 2) by not losing your rings. If you do lose your rings, when you pass a checkpoint, intentionally die, then continue through the level without losing any rings. This works about 80% of the time.

Easy Emeralds:
Enable the "Debug mode" code. At the beginning of the level, create 50 rings and have Sonic collect them. Then, take Sonic to the end of the stage where you the giant ring. In the special stage, turn Sonic into an item and bring him to the end of the stage where the emerald is located. Turn him back and he will immediately get the Emerald. Repeat this until you have all six.

Get all the same color Emeralds:
Enable the "Debug mode" code. While in Special Zone, transform into something then go as far left and down as possible until Sonic stops shaking. Turn back into Sonic. You will fall to a place which is spinning. Look around to find every different Emerald. Note: If you fall off this place, you will fall back to your original location. To prevent this, transform and repeat the process. This works in every Special Zone.

Scrap Brain 3: Shortcut:
To pass Scrap Brain 3 in a very short amount of time, press the button at the beginning of the level, and jump over the bridge to go in the path below the bridge. Jump over all the pits. By the last pit, fall down, and go up the path on the right until you see the red jumper. The jumper brings you to the next level.

Green Hill Zone 3: Flicky reference:
On Green Hill Zone Act 3, just after Sonic steps on the cap to explode the rocket ship, animals pop out. One is a rabbit, and the other is a blue bird who appears to be Flicky, who is from another classic SEGA game, Flicky.

Star Light Zone Act 1: Secret stash:
Enable the "Debug mode" code. If necessary, use the level selection menu to go to the level. Run to the first wall you find, which should have a bomb enemy. Press B button and go through the wall so that you are between two green walls. Either press B again or just fly down to find three ring boxes and an invincibility box. Note: If you use the invincibility and press B, all the sparkles will stay where they last appeared. If you press B again, you will continue the time from last time you pressed B. This lets you use invincibility whenever desired. Note: The time with invincibility will eventually run out.

Reset clock:
If you are running out of time, go to a checkpoint. Once you get the checkpoint, press Start and select "Quit". Then at the main menu, select "Restart". You will resume at the checkpoint with the time reset, allowing you to continue. Note: "Restart" is a new option that will appear when you select the "Quit" option during a level.


Gameplay footage - Greenhill Speedrun: