Sonic & Knuckles is a platformer released for the Sega Genesis worldwide on 18 October 1994. It was developed by Sega Technical Institute in California, directed by Hirokazu Yasuhara and produced by Yuji Naka. Sonic 3 and Sonic & Knuckles were originally one game: the team split it because cartridges were too small and Sega wanted a release in time for a McDonald's promotion in the US.
The cartridge is famous for its lock-on hatch. Placing Sonic 3 on top creates the combined game Sonic 3 & Knuckles, Sonic 2 makes Knuckles playable in Sonic 2, and the first Sonic the Hedgehog unlocks the Blue Sphere minigame.
Sega backed the launch with a reported $45 million marketing campaign, compared with a typical $5 million at the time. The Genesis version sold at least 1.24 million copies in the US, and Sonic 3 and Sonic & Knuckles together sold about 4 million cartridges. In 2022 the game returned as part of Sonic 3 & Knuckles in Sonic Origins.1
Names and releases
| Region | Title on the box | Platform | Date | Publisher | Src |
|---|---|---|---|---|---|
| NA | Sonic & Knuckles Collection | Windows | Mar 14, 1997 | Sega | 1 |
| WW | Sonic & KnucklesWikipedia gives a single worldwide date | Genesis | Oct 18, 1994 | Sega | 1 |
| JP | ソニック&ナックルズJapanese release; Wikipedia gives only the worldwide date of 18 October 1994 | Genesis | 1994 | Sega | 1 |
| JP | Sonic & Knuckles Collection | Windows | Feb 14, 1997 | Sega | 1 |
| EU | Sonic & Knuckles Collection | Windows | Mar 20, 1997 | Sega | 1 |
| WW | Sonic JamCompilation; adds Normal and Easy remix modes | Saturn | 1997 | Sega | 1 |
| WW | Sonic's Ultimate Genesis CollectionCompilation for Xbox 360 and PS3; without lock-on | Xbox 360 | 2009 | Sega | 1 |
| WW | Sonic Classic CollectionCompilation | Nintendo DS | 2010 | Sega | 1 |
| WW | Sonic 3 & KnucklesSteam; delisted when Sonic Origins was released | Windows | January 2011 | Sega | 1 |
| WW | Sonic OriginsRetro Engine version of Sonic 3 & Knuckles by Simon Thomley (Headcannon); also on Switch, PS4, PS5, Xbox One and Series X|S | Windows | 2022 | Sega | 1 |
Also known as: ソニック&ナックルズ JP1Sonikku ando Nakkuruzu JP1Sonic 3 & Knuckles WW1Sonic & Knuckles Collection WW1
Box art by region
NA Sonic & Knuckles Collection 
EU Sonic & Knuckles Collection
Box art © its publishers, shown to identify each release. Scans: libretro-thumbnails.
Version differences
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ContentGenesis cartridge
The cartridge has a lock-on slot. With Sonic 3 it becomes Sonic 3 & Knuckles (Knuckles in Sonic 3's levels, Tails in Sonic & Knuckles' levels, saving, Super Emeralds and Hyper forms); with Sonic 2 it makes Knuckles playable; with the first Sonic or other Genesis games it unlocks Blue Sphere.1
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ContentXbox 360/PS3 (2009)
The Sonic's Ultimate Genesis Collection version has no lock-on feature; the developers blamed tight development time.1
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ContentWii Virtual ConsoleXbox Live Arcade
The digital Wii and Xbox 360 versions unlock lock-on content only if the related games are also owned on the same system.1
Where to play legally today
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Steam Purchase
Reception
Reviews were generally positive, praising the replay value and the lock-on technology, although some critics found it very similar to Sonic 3. Electronic Gaming Monthly made it Game of the Month and IGN gave it 9/10. The Genesis version sold at least 1.24 million copies in the US.1
Sources
Checked: 2026-10-13Text reviewed: 2026-10-13
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