Cheats

Sonic 2 Prototype Cheats

Level Select

What it does: Allows you to start a new game from any level.

Simon Wai Beta (Sonic 2 Beta): On the title screen, hold and press .	Nick Arcade Prototype On the title screen, press .
Sonic 2 beta 4: On the title screen, hold and press .	Sonic 2 beta 5: On the title screen, hold and press .
Sonic 2 betas 6, 7, 8: On the title screen, press , select 1 Player, and hit +. Beta 6 uses the beta 5 level select screen; betas 7 and 8 use the final.

Debug Mode

What It Does: Allows you to place objects in the game, and fly around to navigate freely.

Simon Wai Beta: On the title screen, press . The s can be placed anywhere before the final .	Nick Arcade Prototype: On the title screen, press .
Sonic 2 betas 4 and 5: Debug is always enabled; just go into the level select screen, select a level, and hold .	Sonic 2 beta 6: On the title screen, hit , , , , , , , , , , , , highlight 1 Player, then press +.
Sonic 2 betas 7 and 8: On the title screen, hit , , , , , , , , highlight 1 Player, then press +.

You'll hear a ring sound if you enter the code correctly. Alternatively, you could download a savestate which will take you to the level select screen with debug enabled.

Select a level, hold A until the level shows up.

Once in the game, the buttons now behave differently:

	Cycle through objects forward (when debug is on)
	Toggle debug mode on/off
	Place selected object (when debug is on)
Hold +	Cycle through objects backwards (when debug is on)

Sonic, while turned into an object, can fly through walls and is not subjected to enemy attacks.

The HUD shows different information when in debug.

1. Object's x-coordinate (hex)
2. Object's y-coordinate (hex)
3. Time in seconds (hex)
4. Timer that bounces back and forth between 0000 and 0080 every three seconds (hex)
5. Number of sprites on screen (dec)
6. Rings counter (dec)

The origin, (x,y) = (0000,0000), is located at the upper-left hand corner of a level.

Remember the debug HUD is different for other versions of Sonic.

Luigi Link has posted the

Debug Guide to Sonic 2 Beta, which is definitely worth the reading!

Two-Player Split-Screen

What It Does: Allows 1P to control Sonic on the top-half of the screen, and 2P to control Tails on the bottom-half.

Select a level that has no water, hold until the level shows up. Some levels, such as Metropolis Zone, may not work properly.

Notice Tails has Sonic's icon.

Night Mode

What It Does: Darkens parts of the screen.

Select a level, hold until the level shows up.

Objects on the Plane A High and Plane B High layers are highlighted, whereas those in the Plane A Low and Plane B Low layers are shadowed.

What's the point?

Luigi Link explained on the message board how this mode is useful to Sonic Team for debugging.