Sonic Roms Guide -- Genesis (Sonic & Knuckles)

Lock on the first game and you get...well, basically nothing. But combine Sonic & Knuckles with the second or third games of the series and the fun really begins. You could play it standing alone and still have a good time, of course, but you can also maximize your replay value by ravaging through Sonic 2 as Knuckles or tearing through 14 zones in the 32 megabit monster we know and love as Sonic 3 & Knuckles.

Rom Variations

Sonic & Knuckles (International) (1994)
If you, for whatever reason, choose to play the game without the assistance of Sonic 3, you'll find that you're limited to just Sonic or Knuckles, the game is lacking a save feature, there are half the number of emeralds, and the endings are slightly different. This is actually less exciting than it sounds.

Related Roms

Sonic Special Stages (International) (1994)
When locked on to the Sonic & Knuckles cartridge, the original Sonic seems to behave just like any other cart you could lock on (we'll excuse the animation and color for simplicity's sake, alright?). If you hold all three buttons down, however, you'll enter a bonus game where you face 134,217,728 sphere special stages...if you make it through all of these for whatever reason you go back to the beginning. Argh! The data for this game is stored in S&K, so a null rom was used in place of Sonic 1 to keep the file size down and to reduce confusion (since there are two regional variations of the regular Sonic rom).

Knuckles in Sonic the Hedgehog 2 (International) (1992/1994)
It may have taken a while for us to figure out how to create a rom of this, but doesn't that make it that much more fun to have? Well, in any case, locking on Sonic 2 to Sonic & Knuckles allows you to play Knuckles through the zones of Sonic 2 with only a few changes in layout and the palette. Pretty cool considering we just got a hundred and thirty four million randomly generated sphere special stages for Sonic 1.

Sonic 3 & Knuckles (International) (1994)
This is the only way to play Sonic 3 or Sonic & Knuckles (since it adds Knuckles and S&K to Sonic 3, and Tails and a save feature to S&K). When you lock on a cart to Sonic & Knuckles, the Genesis treats it as one large rom (when it's actually two separate roms, or even three when you lock on Sonic 2). This one large chunk of data is impossible to dump, but it is quite practical to combine both the Sonic 3 and Sonic & Knuckles roms together and apply some basic hex editing to get the save feature to work, which is what was done here.