Sonic & Knuckles

Sonic & Knuckles is a stand-alone expansion pack from Sonic the Hedgehog 3 that is a good game in its own right, but when combined with Sonic 3 becomes what could arguably be the best Sonic game ever.

Level Select


The level select can be accessed by starting the game and grabbing one of the lifts in Mushroom Hill Zone. Once you have grabbed a lift, press Left, Left, Left, Right, Right, Right, Up, Up, Up. If done correctly, you should hear a chime.

When paused, you can perform the following actions:
 * A - Return to title screen
 * B - Play at half-speed
 * C - Advance by one frame

Press Start to pause, then A to return to the title screen. At the title screen, press A + Start to access the level select. From there, you can press C to choose between Sonic (01) and Knuckles (03) only, and trying to select Sonic & Tails (00) or Tails (02) will give you Sonic alone. The Sonic 3 zones are also listed here, but choosing any of them will redirect you to Mushroom Hill. Entries in the sound test which will normally have songs only heard in Sonic 3 are empty and unplayable.

Notes about the levels:
 * Lava Reef Act 3 goes to the boss room. Knuckles cannot select this level.
 * Lava Reef Act 4 goes to Hidden Palace zone. Each character goes to their respective entrance in the level.
 * Sky Sanctuary Act 1 is Sonic's level and Act 2 is Knuckles'. Sonic cannot go to Knuckles' level and vice-versa.
 * Knuckles can enter Death Egg, but he cannot defeat the Act 1 boss (he cannot jump high enough to hit the boss in the first phase).
 * If Sonic beats The Doomsday Zone, the bad ending will play.
 * The Doomsday Act 2 leads to the final boss.
 * Knuckles cannot enter either level of The Doomsday.
 * Bonus 1 goes to the Glowing Spheres bonus game. Bonus 2 goes to the Slot Machine Bonus Game. Finishing each stage will restart it.

Debug Mode
Debug mode cannot be unlocked by normal means. It can only be unlocked using two means:
 * 1) By using the Game Genie code, then pressing A + Start on the title screen or when in the level select.
 * 2) By utilizing a glitch in Sonic 3 & Knuckles whereby placing a long string of "S" monitors in a row using Debug Mode, followed by spindashing into them, will cause the game to crash with a garbled screen. Pressing the Start button on this screen will load Sonic & Knuckles with level select and debug mode enabled. Using the Wii Virtual Console's "Lock-on Menu", it is shown that the game still thinks that it's locked on to Sonic 3.

When in debug mode there you can enter both normal and edit mode in-game. Normal mode is similar to normal gameplay but with added debug features while edit mode is a mode where you can place objects anywhere in the level.

When in normal mode:
 * Press A to reverse gravity (reaching the top of the level will kill you as if you fell off a bottomless cliff).
 * Press B to enter edit mode.
 * Press B + C to play through all the frames of the current characters' animations. (May work in edit mode, needs testing!)

When in edit mode:
 * The coordinates of the current object are shown by the top line of hex digits in the HUD.
 * The coordinates of the current viewport are shown by the bottom line of hex digits in the HUD.
 * Press A to cycle forwards through the object list.
 * Press A + C to cycle backwards through the object list.
 * Press B to enter normal mode.
 * Press C to place the current object shown.

You can use debug mode to enter any level a character would normally not be able to enter (see above), though in some cases this causes player sprites to become corrupted.

Entering edit mode during some parts of the game (such as the light tubes in Death Egg) will crash the game.

8th Special Stage
If Sound Test is enabled, and any of the Special Stage options is selected, Sonic or Knuckles is taken to the 1st Special Stage. The end of it however, spawns a Yellow Super Emerald. This is when the special stage is marked as clear, but the normal Chaos Emerald amount doesn't rise. The Super Emerald amount will rise, but it has pretty much no effect due to Super Emeralds being unobtainable. This bug will allow for the 8th Emerald to be collected once the other six have, though.

Tails
As with Knuckles being unavailable in Sonic 3 but with a few leftovers, Tails is not available in this game. Unlike Knux in Sonic 3, however, he is in actual playable form! Unfortunately, most of his sprites are missing.

If the PAR code is used in Sonic & Knuckles, Tails will be usable, but just about every sprite of his except the transformation sprite will be missing, basically rendering him invisible (unlike when a savestate is used; a different, glitchy sprite is used in place of Tails' original one). There are two exceptions: Tails' sprites used at the end of Sky Sanctuary Zone to run around the collapsing pillar are actually stored in the S&K ROM, and therefore are visible. The same sprites are also used in the same context in Lava Reef Zone. Additionally, Tails' hanging sprites from Sky Sanctuary are also visible.

Hidden Palace's Hidden Area
There's a hidden area in Hidden Palace Zone that is only accessible by debug mode or having Tails in Sonic 3 & Knuckles.

Just before entering the inside of Hidden Palace, fly from the two steps left until a ledge is reached. Walk left and six power-up monitors will appear, mostly shield monitors (Ring, Bubble, Fireball). In some of the S&K prototypes, an "S" monitor is present instead of the Speed Shoes.

If you run right, leap off the ledge, and keep running right you will find two Ring monitors and a 1-up monitor. (video)