Difference between revisions of "Sonic CD Plus Plus"
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{{Hack | {{Hack | ||
|screen=SCDPP.png | |screen=SCDPP.png | ||
| − | |date=June | + | |date=20 June 2009 |
| system=[[Sega Mega CD]] | | system=[[Sega Mega CD]] | ||
| − | |originalgame=Sonic CD | + | |originalgame=Sonic the Hedgehog CD |
| credits=[[qiuu]], [[snkenjoi]] | | credits=[[qiuu]], [[snkenjoi]] | ||
|visualmods= | |visualmods= | ||
| Line 11: | Line 11: | ||
|advenginemods=yes}} | |advenginemods=yes}} | ||
| − | '''''SonicCD++''''' (or '''''Sonic CD Plus Plus''''') is a hack of ''[[Sonic CD]]'' by [[qiuu]] and [[snkenjoi]] | + | '''''SonicCD++''''' (or '''''Sonic CD Plus Plus''''') is a hack of ''[[Sonic the Hedgehog CD]]'' by [[qiuu]] and [[snkenjoi]], adding the ''[[Sonic the Hedgehog 2 (16-bit)]]'' style [[Spin Dash]] and the newer [[Homing Attack]] into the game. This enables the gameplay to be significantly speedier, while ''Sonic CD'' is known to be one of the more slow-paced games in the classic ''[[Sonic the Hedgehog|Sonic]]'' series. |
| − | == | + | ==New features== |
| − | * ''Sonic 2'' | + | * ''[[Sonic the Hedgehog 2 (16-bit)|Sonic the Hedgehog 2]]'' style [[Spin dash]] (hold {{Down}} to duck, press {{A}}/{{B}}/{{C}} to charge) |
| − | * | + | * ''[[Sonic the Hedgehog Megamix]]'' style homing attack (pressing {{A}}/{{B}}/{{C}} while in a ball) |
* Air Roll (when in the air without being in a ball, press {{A}}/{{B}}/{{C}}/{{Down}} to curl into a ball) | * Air Roll (when in the air without being in a ball, press {{A}}/{{B}}/{{C}}/{{Down}} to curl into a ball) | ||
| − | * Air | + | * [[SCHG How-to:Remove the Speed Cap|Air speed cap removed]] |
| + | ==Development history== | ||
| − | + | Everything started with [[snkenjoi]] asking [[qiuu]] whether he had attempted making a ''[[Sonic the Hedgehog CD]]'' hack yet (which he had of course not), upon which qiuu brought up [[Mad Echidna]]'s {{LinkRetro|topic=11507|title=offer from a year back}} to pay $100 to the first person to put the [[Spin Dash]] from ''[[Sonic the Hedgehog 2 (16-bit)]]'' spin dash into ''Sonic CD''. While qiuu doubted that it was up to date, it got snkenjoi motivated to start attempting to insert the move into the game. So, had it not been for either of these two (snkenjoi and MadEchidna), the project wouldn't have even started in the first place. | |
| − | Everything started with snkenjoi asking qiuu whether he had attempted making a ''Sonic CD'' hack yet (which he had of course not), upon which qiuu brought up [[Mad Echidna]]'s {{LinkRetro|topic=11507|title=offer from a year back}} to pay $100 to the first person to put the ''Sonic 2'' spin dash into ''Sonic CD''. While qiuu doubted that it was up to date, it got snkenjoi motivated to start attempting to insert the move into the game. So, had it not been for either of these two (snkenjoi and MadEchidna), the project wouldn't have even started in the first place. | ||
| − | So for some time, qiuu mostly kept passive, merely giving advice to snkenjoi every now and then | + | So for some time, qiuu mostly kept passive, merely giving advice to snkenjoi every now and then--but seeing the progress, he felt more and more like joining in. So parallel to snkenjoi's work, he started writing a tool that would make finding and inserting new content into the ''Sonic CD'' [[wiki:ISO image|ISO image]] a lot easier. Being done with that, qiuu set up an [[wiki:Apache Subversion|SVN]] repository marking the starting point of the two's collaboration. With the Spin Dash already halfway implemented, qiuu implemented the [[Homing Attack]], which turned out to be significantly less difficult to add. From here, it was simply a case of further developing the code in order to insert the additional features into the game--and notably, repeatedly trying to find free space to fit them in! The authors thank [[Tweaker]] for helping with this by mentioning the [[Game Secrets:Sonic the Hedgehog CD#Unused sprites|unused Sonic sprites]], and [[MKAmeX]] for contributing Spin Dash sprites for the shrunken form Sonic assumes during some of [[Metallic Madness Zone]]. |
| − | Despite only taking around a week | + | Despite only taking around a week to accomplish, most of the development time was spent fixing bugs that had appeared. The final touch, again upon Tweaker's suggestion, was adding the air roll, which took barely ~20 minutes in the end. |
In the end, it was a fun challenge. | In the end, it was a fun challenge. | ||
==Insight into the technical aspects of the hacking process== | ==Insight into the technical aspects of the hacking process== | ||
| + | Contrary to what one may believe, no working disassembly was made of any of the [[MMD]] files within the ''Sonic CD'' [[wiki:ISO image|ISO image]], though one or two were used as a reference at times. In essence, the technique that was used is [[sega:Hexadecimal|hex]] hacking without a [[sega:Hex editor|Hex editor]]: Code that is to be inserted is written in [[sega:assembly language|assembly language]], and then assembled into bytecode. The location the code or data is inserted into is automatically detected by the program, which identifies routines by their bytecode. From here, the new code can be inserted into locations of known unused space. If a section of the code refers to routines or data from within the MMD, it additionally has to be patched after having been assembled. For the game to run this code, either existing jumps in game have to be hijacked, or code must be overwritten to point to the locations of the injected code, with the overwritten data being relocated at the jump destination to ensure correct program flow. | ||
| − | + | [[wiki:Source code|Source code]] is available upon request. | |
| − | |||
| − | |||
| − | Source code is available upon request. | ||
==Credits== | ==Credits== | ||
| − | * qiuu & snkenjoi: main coding and implementation | + | * [[qiuu]] & [[snkenjoi]]: main coding and implementation |
| − | * | + | * [[MKAmeX]]: [[sega:sprite]]s for the [[Spin Dash]] of small Sonic |
| − | * | + | * [[Mad Echidna]]: motivation through his {{LinkRetro|topic=11507|title=$100 code bounty for the ''S2'' Spin Dash in ''SCD''}} |
| − | * Tweaker: various suggestions and advice | + | * [[Tweaker]]: various suggestions and advice |
==Download== | ==Download== | ||
| Line 59: | Line 57: | ||
}} | }} | ||
| − | ==External | + | ==External links== |
| − | {{LinkRetro|topic=15737|title=Sonic CD++ | + | {{LinkRetro|topic=15737|title=Sonic CD++ release topic}} at [[Sonic Retro]] Message Board |
| + | {{LinkRetro|topic=11507|title=Mad Echidnas's topic offering a $100 bounty for ''S2'''s Spin Dash in ''SCD''}} | ||
[[Category:Hacks]] | [[Category:Hacks]] | ||
Revision as of 10:42, 22 June 2010
| Sonic CD Plus Plus |
|---|
| Last release: 20 June 2009 |
| System: Sega Mega CD |
| Original game: Sonic the Hedgehog CD |
| Credits: qiuu, snkenjoi |
SonicCD++ (or Sonic CD Plus Plus) is a hack of Sonic the Hedgehog CD by qiuu and snkenjoi, adding the Sonic the Hedgehog 2 (16-bit) style Spin Dash and the newer Homing Attack into the game. This enables the gameplay to be significantly speedier, while Sonic CD is known to be one of the more slow-paced games in the classic Sonic series.
Contents
New features
- Sonic the Hedgehog 2 style Spin dash (hold
to duck, press 
/
/
to charge) - Sonic the Hedgehog Megamix style homing attack (pressing // while in a ball)
- Air Roll (when in the air without being in a ball, press /// to curl into a ball)
- Air speed cap removed
Development history
Everything started with snkenjoi asking qiuu whether he had attempted making a Sonic the Hedgehog CD hack yet (which he had of course not), upon which qiuu brought up Mad Echidna's
So for some time, qiuu mostly kept passive, merely giving advice to snkenjoi every now and then--but seeing the progress, he felt more and more like joining in. So parallel to snkenjoi's work, he started writing a tool that would make finding and inserting new content into the Sonic CD ISO image a lot easier. Being done with that, qiuu set up an SVN repository marking the starting point of the two's collaboration. With the Spin Dash already halfway implemented, qiuu implemented the Homing Attack, which turned out to be significantly less difficult to add. From here, it was simply a case of further developing the code in order to insert the additional features into the game--and notably, repeatedly trying to find free space to fit them in! The authors thank Tweaker for helping with this by mentioning the unused Sonic sprites, and MKAmeX for contributing Spin Dash sprites for the shrunken form Sonic assumes during some of Metallic Madness Zone.
Despite only taking around a week to accomplish, most of the development time was spent fixing bugs that had appeared. The final touch, again upon Tweaker's suggestion, was adding the air roll, which took barely ~20 minutes in the end.
In the end, it was a fun challenge.
Insight into the technical aspects of the hacking process
Contrary to what one may believe, no working disassembly was made of any of the MMD files within the Sonic CD ISO image, though one or two were used as a reference at times. In essence, the technique that was used is hex hacking without a Hex editor: Code that is to be inserted is written in assembly language, and then assembled into bytecode. The location the code or data is inserted into is automatically detected by the program, which identifies routines by their bytecode. From here, the new code can be inserted into locations of known unused space. If a section of the code refers to routines or data from within the MMD, it additionally has to be patched after having been assembled. For the game to run this code, either existing jumps in game have to be hijacked, or code must be overwritten to point to the locations of the injected code, with the overwritten data being relocated at the jump destination to ensure correct program flow.
Source code is available upon request.
Credits
- qiuu & snkenjoi: main coding and implementation
- MKAmeX: sega:sprites for the Spin Dash of small Sonic
- Mad Echidna: motivation through his $100 code bounty for the S2 Spin Dash in SCD
- Tweaker: various suggestions and advice
Download
|
Download Sonic CD++ US version (18.51 MB) (info) EU version (17.2 MB) (info) JP version (17.2 MB) (info) Option Select Tool (11 kB) (info)
|
External links