Sonic Classics

Not to be confused with the website Sonic Classic or the fangame Sonic the Hedgehog Classic.

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Sonic Classics
System(s): Sega Mega Drive
Publisher: Sega (US, Europe), Tec Toy (BR), HiCom (KR)
Developer: Sega
Game total: 3
Genre: Compilation
Number of players: 1-2
Release Date RRP Code Rating US 1997-04-24 $? 1190 EU 1995-08 €? 1190-50 UK 1995-08 £? 39.99 AU 199x $? FSON16SMC AU (3 in 1) 199x $? ? BR 1997-06 R$? 042780 KR 1997 ₩? ? PT 199x  ? MDJ1190 NZ 199x  ? ?

Sonic Classics, known as Sonic Compilation in Europe, is a compilation of three games for the Sega Mega Drive stored on a single cartridge: Sonic the Hedgehog, Sonic the Hedgehog 2, and Dr. Robotnik's Mean Bean Machine. Sonic Classics was included as a pack-in title with some editions of the Mega Drive hardware in Europe. The game was not released in Japan.

The three games appear in almost exactly the same form as in their original release, with the exception of some revisions to their code (see their individual sections below). The only new content is a game selection menu, controlled by using the and directions on the D-pad and new sprite renderings of the box art for each of the three games. Once a game is selected, players are not able to go back to the menu unless the console is reset or turned off and on again.

This game is one of two that, when "locked on" with Sonic & Knuckles, will enable players to play the entire Blue Sphere game, instead of just one level. The other game that enables this is the standalone version of Sonic the Hedgehog. This is because when locked-on to a ROM larger than 2MB, Sonic & Knuckles maps the last 2MB of the locked-on ROM rather than the first 2MB, and Sonic Classics happens (or was designed?) to put Sonic the Hedgehog at the 2MB mark. This is a quirk in the Sonic & Knuckles cartridge's mapper, which is not reproduced in emulators.

The background music and chime heard when a game is selected in the menu are from Dr. Robotnik's Mean Bean Machine itself.

Games

Sonic the Hedgehog

This version of the original game is the same as the standard worldwide REV00 release, except for a new bug in Scrap Brain Zone involving the cycling palette. The bug is caused by the fact that the pointers for palette data are only two bytes long. In Sonic 1 alone, this isn't a problem because palette data lies within the first 0xFFFF of the ROM. However, in Sonic Classics, the data comes after 0x10000, so part of the address is truncated in the pointer, causing incorrect data to be loaded.

Sonic the Hedgehog 2

It was conjectured for some time that the version of Sonic 2 included in Sonic Classics was the former game's REV02, i.e. a second update to its code that had been officially (if silently) made by Sega themselves. This was shown conclusively in June of 2012 when Esrael, who was now using this version as the code-base for his famed hack Sonic 2 Delta, released a ROM of the game extracted to work on its own and followed this shortly thereafter with his disassembly of said ROM, which demonstrated that Sega had implemented various bug-fixes and other alterations to the code in time for Sonic Classics.

Issues

There are several issues with the version of Sonic 2 included in this compilation. Contrary to popular belief, these bugs are specific to Sonic Classics, and are not present in any other known instance of REV02 (Sonic 2 for Mega Play, Knuckles in Sonic 2, Sonic Jam).

These bugs are seemingly caused by corrupted constants in the game's source code, with all of them relating to nonsensical bitmasks.

• The sparks that Mecha Sonic leaves when he slides are erroneously not mirrored when he turns around.
• The above issue also affects Grabber's legs.
• Sonic/Tails is no longer able to Spin Dash off the Tornado in Sky Chase Zone, and instead briefly hovers in the air.
• In Wing Fortress Zone, the vertical conveyor belt platforms no longer cause Sonic/Tails to fall when they retract into the wall while they're stood on it. This causes them to be able to walk on the air.

The original cheat codes contained on the cartridge still work here, but the game enhancer codes do not.

Hidden content

Main article: Sonic Classics/Hidden content

Manuals

Main article: Sonic Classics/Manuals

Physical scans

Mega Drive, US
Cover
Cart File:SonicClassics MD US manual.pdf Manual

Mega Drive, EU
Cover
Cart File:SonicClassics MD EU manual.pdf Manual

Mega Drive, UK
Cover

Mega Drive, PT
Cover

Mega Drive, PT (alt)
Cover

Mega Drive, GR (Zegetron)

Mega Drive, AU
Cover
Cart File:SonicClassics MD AU manual.pdf Manual

Mega Drive, AU (3 in 1)
Cover
Cart

Mega Drive, BR
Cover
Cart File:SonicClassics MD BR manual.pdf Manual

Mega Drive, KR
Cover
Cart File:SonicClassics MD KR manual.pdf Manual

Mega Drive, NZ

Mega Drive, ZA
Cover

Technical information

ROM dump status

System	Hash	Size	Build Date	Source	Comments
✔	CRC32 8c70b84e MD5 1e8c38878d4184977718b8b3c90642b8 SHA-1 109e6d7b31d00fbdb9d4ecb304d4ea19e96c8607	3MB	1995-06	Cartridge (EU)	REV00
✔	CRC32 95b5e8d7 MD5 59a5029e58a43c40b715fb8906e6634f SHA-1 2196cbe754cfcd1d7bbbd0a8a45ae44de4deb2fb	3MB	1997-01	Cartridge (US/EU)	REV01

References

Sonic the Hedgehog games for the following systems

1991  Sonic the Hedgehog | Sonic Eraser     1992  Sonic the Hedgehog 2     1993  Sonic the Hedgehog CD | Dr. Robotnik's Mean Bean Machine | Sonic Spinball     1994  Sonic the Hedgehog 3 | Sonic & Knuckles     1995  Chaotix | Sonic Classics     1996  Sonic 3D: Flickies' Island     2024  Sonic the Hedgehog 3 (promotional cartridge)      Prototypes  Sonic the Hedgehog | Sonic the Hedgehog 2 | Sonic the Hedgehog CD | Sonic Spinball | Dr. Robotnik's Mean Bean Machine | Sonic the Hedgehog 3 | Sonic & Knuckles | Knuckles in Sonic 2 | Chaotix | Sonic 3D: Flickies' Island  Unreleased  Sonic the Hedgehog (Mega-CD) | Sonic the Hedgehog 2 CD | Sister Sonic | Treasure Tails | Sonic-16 | Sonic the Hedgehog 3 Limited Edition | Sonic Sports | Sonic Mars