ROM hacking

Last updated

ROM hacking is the process of modifying a ROM image or ROM file of a video game to alter the game's graphics, dialogue, levels, gameplay, and/or other elements. This is usually done by technically inclined video game fans to improve an old game of importance, as a creative outlet, or to make new, unofficial games using the old game's engine. ROM hacks either re-design a game for new, fun gameplay while keeping most if not all of the items the same, as well as unlocking/reimplementing features that existed in the game's code but are not utilized in-game.

Contents

ROM hacking is generally accomplished through use of a hex editor (a program for editing non-textual data) and various specialized tools such as tile editors, and game-specific tools which are generally used for editing levels, items, and the like, although more advanced tools such as assemblers and debuggers are occasionally used. Once ready, they are usually distributed on the Internet for others to play on an emulator or games console. [1]

Fan translation (known as "translation hacking" within the ROM hacking community) is a type of ROM hacking; there are also anti-censorship hacks that exist to restore a game to its original state, which is often seen with older games that were imported, as publishers' content policies for video games (most notably, Nintendo's) were much stricter in the United States than Japan or Europe; as well as randomizers for certain games which shuffle entity placements. [2] Although much of the method applies to both types of hacking, this article focuses on "creative hacking" such as editing game levels.

Communities

Most hacking groups offer web space for hosting hacks and screenshots (sometimes only hosting hacks by the group's members and hosting almost any hack), a message board, and often have an IRC channel.

Methods

Having been created by many different programmers or programming teams, ROM data can be very diverse.

Hex editing

A hex editor is one of the most fundamental tools in any ROM hacker's repertoire. Hex editors are usually used for editing text, and for editing other data for which the structure is known (for example, item properties), and Assembly hacking.

Editing text is one of the most basic forms of hacking. Many games do not store their text in ASCII form, and because of this, some specialized hex editors have been developed, which can be told what byte values correspond to what letter(s) of the alphabet, to facilitate text editing; a file that defines these byte=letter relationships is called a "table" file. Other games use simple text compression techniques (such as byte pair encoding, also called dual tile encoding or DTE, in which certain combinations of two or more letters are encoded as one byte) which a suitably equipped hex editor can facilitate editing.

A hex editor is the tool of choice for editing things such as character/item properties if the structure and location of this data are known and there is no game-specific editor for the game that can edit this information. Some intrepid hackers also perform level editing with a hex editor, but this is extremely difficult (except on games whose level storage format closely resembles how it is presented in a hex editor).

Graphics editing

Another basic hacking skill is graphics hacking, which is changing the appearance of the game's environments, characters, fonts, or other such things. The format of graphics data varies from console to console, but most of the early ones (NES, Super NES, Game Boy, etc.) store graphics in tiles, which are 8x8-pixel units of data, which are arranged on-screen to produce the desired result. Editing these tiles is also possible with a hex editor, but is generally accomplished with a tile editor (such as Tile Layer or Tile Molester), which can graphically display the ROM data, as well as finding and editing tiles.

Graphics hacks can range from simple edits (such as giving Mario an afro or Luigi a golf club) to "porting" characters from one game to another (such as creating pixelated "retro-styled" sprites of later generation Pokémon for use in Generation I-V Pokémon games [3] ), to full-blown thematic changes (usually with accompanying palette changes; see below).

More sophisticated graphics hacking involves changing more than just tiles and colors, but also on how the tiles are arranged, or tile groups generated, giving more flexibility and control over the final appearance. This is accomplished through hex editing or a specialized tool (either for a specific game or a specific system). Examples of graphics hacks include the incomplete Pokémon Torzach, a hack of Pokémon FireRed which attempted to add a whole new generation of Pokémon and tiles to the game, [4] and Super Mario Land 2 DX: 6 Golden Coins, a full-color version of the original game which added, among others, full-color support (the original game was greyscale-only) as well as fixes with screen flickering issues that were present in the original game. [5]

Palette editing

Another common form of hacking is palette hacking, where color values are modified to change the colors a player sees in the game (this often goes hand-in-hand with graphics hacking); Palette values are commonly stored in Hex. This is fairly easy for NES games, the graphics of which use a pre-defined set of colors among which a game selects (using a YIQ-based color palette); palette hacking in this case entails changing which of those colors are selected. The matter is slightly more complicated with Super NES and Sega Mega Drive/Genesis games, as well as games for other systems, which store absolute RGB color values. Palette editors are usually simple and often are with level editors or game-specific graphics editors.

Level editing

One of the most popular forms of ROM hacking, level editing entails modifying or redesigning a game's levels or maps. This is almost exclusively done with an editor specially tailored for a particular game (called a level editor ). Level edits can be done to make the game more challenging, to alter the flow of the game's plot, or just to give something new to an old game. Combined with extensive graphics hacking, the game can take on a very different look and feel.

Data editing

A core component of many hacks (especially of role-playing video games) is editing data such as character, item, and enemy properties. This is usually done either "by hand" (with a hex editor) if the location and structure of the data is known, or with a game-specific editor that has this functionality. Through this, a hacker can alter how weapons work, how strong enemies are or how they act, etc. This can be done to make the game easier or harder or to create new scenarios for the player to face.

Assembly hacking

The most powerful, and arguably the most difficult, hacking technique is editing the game's actual code, a process called ASM hacking ("ASM" means "assembly", referring to the low-level programming language that gets executed by the CPU). [1] There is no set pattern for ASM hacking, as the code varies widely from game to game, but most skilled ASM hackers either use an emulator equipped with a built-in debugger or tracer, or run the ROM through a disassembler, then analyze the code and modify it using a hex editor or assembler according to their needs. While quite challenging compared to the relatively simple methods listed above, anything is possible with ASM hacking (of course, within the limits of the hardware/software of the gaming platform), ranging from altering enemy AI to changing how graphics are generated. (Of course, the possibilities are still limited by the hacker's ability to comprehend and modify the existing code.)

If the developers used a typed language, the hacker may be able to compile their code for the game in the same language if they have access to a proper compiler. One such example would be using C to hack Nintendo 64 games, since MIPS-GCC can compile code for the Nintendo 64. [6] [7]

Music hacking

Music hacks are relatively rare in most hacks, due to the wide variety of ways games store music data (hence the difficulty in locating and modifying this data) as well as the difficulties in composing new music (or porting music from another game). As music cracking is very uncommon, many hacks do not have any ported/composed music added in. Exceptions to this rule can be found in the most recent Super Mario World hacks where custom musics can have new instruments not found in the original game. Other games that have music hacking as part of their research and hacking communities are the NES Mega Man games, Final Fantasy VI , and the Mega Drive (Genesis) Sonic the Hedgehog games.

As many Game Boy Advance games use the M4A Engine (also called "Sappy Driver") for music, the program SapTapper can be used to hack Game Boy Advance music data. Various other utilities were created to work with the engine such as Sappy 2006.

Another instance of the same engine being used between games is on the Nintendo 64 where most games use the same format; however, they use different sound banks. A utility known as the N64 Midi Tool was created to edit the sequences that the majority of Nintendo 64 games use, though it does not cover the first-party N64 titles that use a slightly different engine, such as Super Mario 64 .

Several Sega Mega Drive/Genesis games [8] use a sound engine unofficially known as "SMPS", [9] which were offered in both 68k and Z80-based versions. As a predominant sound engine used in a variety of Japanese-developed games for the system, this sound engine has been researched for decades by many hackers. [10] As of today, various tools exist [11] to alter the music of games which use the SMPS engine (most notably the Sonic the Hedgehog games in particular), and many of them made their way to the Steam Workshop. [12]

ROM expansion

Generally speaking, a ROM hacker cannot normally add content to a game, but merely change existing content. This limit can be overcome through ROM expansion, whereby the total size of the ROM image is increased, making room for more content and, in turn, a larger game. The difficulty in doing this varies depending on the system for which the game was made. For example, expanding an NES ROM may be difficult or even impossible due to the mapper used by the game. For example, if a mapper allows 16 ROM banks and all of them are used, expanding the ROM further is impossible without somehow converting the game to another mapper, which could be easy or extremely difficult. On the other hand, expanding an SNES game is (relatively) straightforward. To utilize the added space, parts of the game code have to be modified or rewritten (see Assembly hacking above) so the game knows where to look. Another type of ROM expansion that is fairly easy is Game Boy Advance ROMs. The ROMs themselves are generally small, but the memory space available sometimes exceeds it by multiples of up to 17.

Distribution

Once a hack is completed (or an incomplete version is deemed suitable for an interim release) it is released onto the Internet for others to play. The generally accepted way to do this is by making an unofficial patch (in IPS format or others) that can be applied to the unmodified ROM. [1] This, and usually some form of documentation, is put in an archive file and uploaded somewhere. IPS is a format for recording the differences between two binary files (in this case, between the unmodified and hacked ROMs) and is suitable for rom hacks. [13] IPS is still used today for small patches—however, as ROMs became larger, this format became useless, leading to quite a few file formats being created—such as NINJA and PPF (also known as "PlayStation Patch Format"). PPF is still used today, particularly to patch large files such as ISO CD-ROM images as well as Nintendo 64 games. A new patch format, UPS, has also been developed by the ROM hacking community, designed to be the successor to IPS and PPF. [14] A more recent patching format, the APS patching system, has also been developed by a devoted Game Boy Advance ROM hacker. [15] The APS system is more space efficient, is reversible, and is faster than its predecessor. [16]

The purpose of distributing a hack in patch form is to avoid the legal aspects of distributing entire ROM images; the patch records only what has changed in the ROM, hence distributing it does not usually distribute parts of the original game. A patch is also normally drastically smaller than the full ROM image (an NES ROM can run anywhere from 8 KB to 2 MB; a Super NES ROM can run from 256 KB to 6 MB; and Mega Drive/Genesis ROMs can run from 512 KB to 4 MB). As mentioned above, patches usually only contained user-made code changes and not copyrighted code, so they were not illegal to be distributed.

In a novel example of legal distribution, Sega released a Steam-based virtual hub for its previous collection of Mega Drive/Genesis games, entitled Sega Mega Drive Classics Hub . The Hub, besides allowing players to play emulated versions of these older games, takes advantage of Steam's support for user-created content through the Steam Workshop, officially allowing the distribution of ROM hacks of any of the offered games. [17]

Usage

Patched ROMs are often played on emulators, however, it is possible to play patched ROMs on the original hardware. [18] The destination cartridge could be the original cartridge from which the initial unpatched ROM was pulled (which involves replacing the original ROM chip with a new one), or another compatible cartridge of the same type, such as flash cartridges. This is particularly popular for fan translations, homebrew games, prototypes, games for which ROM cartridges were never produced, or for games that require exact timing or other elements of the original hardware that are not available in emulators.

Systems and games

The majority of ROM hacking is done on NES and SNES games (including Sega Mega Drive/Genesis games to an extent), since such games are small and simple compared to games of more advanced consoles such as the Nintendo 64 or Nintendo DS. Games for the Game Boy, Game Boy Color and Game Boy Advance are also popular for hacking, as well as games for the PlayStation to a lesser extent. However, games intended for more recent consoles are not exempt from hacking, and as computers have become faster over time and more programs and utilities have been written, more PlayStation, Nintendo 64 and Nintendo DS hacks have emerged.

Of these, popular games to play are popular games to hack; many hacks have been released of games of the Sonic the Hedgehog series, Mario series (including Mario Bros. , Super Mario Bros. , Super Mario Bros. 2 , Super Mario Bros. 3 , Super Mario Land , Super Mario Land 2: 6 Golden Coins , Super Mario 64 and Super Mario World ), Mario Kart series (most notably Super Mario Kart , Mario Kart Wii , Mario Kart 7 , and Mario Kart DS ), Pokémon series, Chip's Challenge , Castlevania , Final Fantasy , The Legend of Zelda , games from the Mega Man series, Fire Emblem series, EarthBound , Super Metroid , and many others.

A notable hacked arcade game was Street Fighter II: Rainbow Edition , which featured increased game speed and new special moves. The success of this game prompted Capcom to release Street Fighter II: Hyper Fighting as an official response.

Your Sinclair magazine published a monthly column called "Program Pitstop". This focused mainly on cheat hacks for games, but also featured both a level map printer [19] for the original Gauntlet , as well as a full level editor [20] for the same game.

See also

Related Research Articles

<span class="mw-page-title-main">Super Nintendo Entertainment System</span> Home video game console

The Super Nintendo Entertainment System, commonly shortened to Super Nintendo, Super NES or SNES, is a 16-bit home video game console developed by Nintendo that was released in 1990 in Japan and South Korea, 1991 in North America, 1992 in Europe and Oceania and 1993 in South America. In Japan, it is called the Super Famicom (SFC). In South Korea, it is called the Super Comboy and was distributed by Hyundai Electronics. The system was released in Brazil on August 30, 1993, by Playtronic. Although each version is essentially the same, several forms of regional lockout prevent cartridges for one version from being used in other versions.

<span class="mw-page-title-main">Parallax scrolling</span> Technique in computer graphics

Parallax scrolling is a technique in computer graphics where background images move past the camera more slowly than foreground images, creating an illusion of depth in a 2D scene of distance. The technique grew out of the multiplane camera technique used in traditional animation since the 1930s.

Game Genie is a line of video game cheat cartridges originally designed by Codemasters, sold by Camerica and Galoob. The first device in the series was released in 1990 for the Nintendo Entertainment System, with subsequent devices released for the Super NES, Game Boy, Genesis, and Game Gear. All Game Genie devices temporarily modify game data, allowing the player to do things unintended by developers such as, depending on the game, cheating, manipulating various aspects of games, and accessing unused assets and functions. Five million units of the original Game Genie products were sold worldwide, and most video game console emulators for the platforms it was on feature Game Genie code support. Emulators that have Game Genie support also allow a near-unlimited number of codes to be entered whereas the actual products have an upper and lower limit, between three and six codes.

A regional lockout is a class of digital rights management preventing the use of a certain product or service, such as multimedia or a hardware device, outside a certain region or territory. A regional lockout may be enforced through physical means, through technological means such as detecting the user's IP address or using an identifying code, or through unintentional means introduced by devices only supporting certain regional technologies.

In the history of video games, the fourth generation of video game consoles, more commonly referred to as the 16-bit era, began on October 30, 1987, with the Japanese release of NEC Home Electronics' PC Engine. Though NEC released the first console of this era, sales were mostly dominated by the rivalry between Sega and Nintendo across most markets: the Sega Mega Drive and the Super Nintendo Entertainment System. Cartridge-based handheld consoles became prominent during this time, such as the Nintendo Game Boy (1989), Atari Lynx (1989), Sega Game Gear (1990) and TurboExpress (1990).

The fifth generation era refers to computer and video games, video game consoles, and handheld gaming consoles dating from approximately October 4, 1993, to March 23, 2006. For home consoles, the best-selling console was the Sony PlayStation, followed by the Nintendo 64, and then the Sega Saturn. The PlayStation also had a redesigned version, the PSone, which was launched on July 7, 2000.

<i>Zombies Ate My Neighbors</i> 1993 video game

Zombies Ate My Neighbors is a run and gun video game developed by LucasArts and published by Konami for the Super NES and Sega Genesis consoles in 1993.

<i>Flashback</i> (1992 video game) 1992 video game

Flashback, released as Flashback: The Quest for Identity in the United States, is a 1992 science fiction cinematic platform game developed by Delphine Software of France and published by U.S. Gold in the United States and Europe, and Sunsoft in Japan.

<span class="mw-page-title-main">Super FX</span> 3D graphics chip used in Super Nintendo games

The Super FX is a coprocessor on the Graphics Support Unit (GSU) added to select Super Nintendo Entertainment System (SNES) video game cartridges, primarily to facilitate advanced 2D and 3D graphics. The Super FX chip was designed by Argonaut Games, who also co-developed the 3D space rail shooter video game Star Fox with Nintendo to demonstrate the additional polygon rendering capabilities that the chip had introduced to the SNES.

Homebrew, when applied to video games, refers to software produced by hobbyists for proprietary video game consoles which are not intended to be user-programmable. The official documentation is often only available to licensed developers, and these systems may use storage formats that make distribution difficult, such as ROM cartridges or encrypted CD-ROMs. Many consoles have hardware restrictions to prevent unauthorized development.

<i>Bram Stokers Dracula</i> (video game) 1993 video game

Bram Stoker's Dracula is a 1993 video game released for the Mega Drive/Genesis, Nintendo Entertainment System, Super NES, Game Boy, Master System, Sega CD, Game Gear, MS-DOS, and Amiga. It is based on the 1992 film Bram Stoker's Dracula which in turn is based on the 1897 novel Dracula by Bram Stoker. Most versions are platform games. The Sega CD and Amiga releases are beat 'em ups, and the MS-DOS version is a first-person shooter. The Amiga version was released in 1994 for North America and Europe. A CD-ROM version for MS-DOS compatible operating systems was released in 1995.

The Virtual Console is a defunct line of downloadable video games for Nintendo's Wii and Wii U home video game consoles and the Nintendo 3DS family of systems.

<span class="mw-page-title-main">Sega Genesis</span> Home video game console

The Sega Genesis, also known as the Mega Drive outside North America, is a 16-bit fourth generation home video game console developed and sold by Sega. It was Sega's third console and the successor to the Master System. Sega released it in 1988 in Japan as the Mega Drive, and in 1989 in North America as the Genesis. In 1990, it was distributed as the Mega Drive by Virgin Mastertronic in Europe, Ozisoft in Australasia, and Tectoy in Brazil. In South Korea, it was distributed by Samsung Electronics as the Super Gam*Boy and later the Super Aladdin Boy.

<i>Joe & Mac</i> 1991 video game

Joe & Mac, also known as Caveman Ninja and Caveman Ninja: Joe & Mac, is a 1991 run and gun platform game released for arcades by Data East. It was later adapted for the Super NES, Mega Drive/Genesis, Nintendo Entertainment System, Game Boy, Amiga, Zeebo, Nintendo Switch, and PC.

<span class="mw-page-title-main">ROM cartridge</span> Replaceable device used for the distribution and storage of video games

A ROM cartridge, usually referred to in context simply as a cartridge, cart, or card, is a replaceable part designed to be connected to a consumer electronics device such as a home computer, video game console or, to a lesser extent, electronic musical instruments.

<span class="mw-page-title-main">Game backup device</span> Device for backing up ROM information from a video game cartridge

A game backup device, informally called a copier, is a device for backing up ROM data from a video game cartridge to a computer file called a ROM image and playing them back on the official hardware. Recently flash cartridges, especially on the Game Boy Advance and Nintendo DS platforms, only support the latter function; they cannot be used for backing up ROM data. Game backup devices also make it possible to develop homebrew software on video game systems. Game backup devices differ from modchips in that modchips are used in conjunction with systems that use generally available media such as CDs and DVDs, whereas game backup devices are used with systems that use cartridges.

A fan game is a video game that is created by fans of a certain topic or IP. They are usually based on one, or in some cases several, video game entries or franchises. Many fan games attempt to clone or remake the original game's design, gameplay, and characters, but it is equally common for fans to develop a unique game using another as a template. Though the quality of fan games has always varied, recent advances in computer technology and in available tools, e.g. through open source software, have made creating high-quality games easier. Fan games can be seen as user-generated content, as part of the retrogaming phenomena, and as expression of the remix culture.

<i>Fun n Games</i> 1994 video game

Fun 'n Games is a compilation video game developed by Leland Interactive Media and released for the Super NES and Mega Drive/Genesis platforms in 1993 and 1994. In 1995, an updated, redeveloped version of the game was released on the 3DO Interactive Multiplayer and MS-DOS by Williams Entertainment Inc. The North American Super NES version of the game is considered to be one of the more rare games released for the console.

In the video game industry, a console war describes the competition between two or more video game console manufacturers in trying to achieve better consumer sales through more advanced console technology, an improved selection of video games, and general marketing around their consoles. While console manufacturers are generally always trying to out-perform other manufacturers in sales, these console wars engage in more direct tactics to compare their offerings directly against their competitors or to disparage the competition in contrast to their own, and thus the marketing efforts have tended to escalate in back-and-forth pushes.

References

  1. 1 2 3 "Dictionary of ROM hacking terms". ROMhacking.net.
  2. ↑ "The BIG List of Video Game Randomizers". Guillaume Fortin-Debigaré. Retrieved 2020-07-10.
  3. ↑ "Pokemon Rom Hacks List: GBC, GBC & NDS - PokemonCoders". PokemonCoders. 2019-04-13. Retrieved 2023-03-08.
  4. ↑ "Pokemon FireRed ROM Hacks". PokemonCoders.com. 11 March 2019.
  5. ↑ Machkovech, Sam (25 December 2017). "A Christmas gift from Game Boy ROM hackers: Super Mario Land 2 in color". Ars Technica. Retrieved 18 February 2023.
  6. ↑ "vg64tools - Project Hosting on Google Code" . Retrieved 2009-09-09.
  7. ↑ "Super Mario 64: Pong Of Death (messiaen)". Archived from the original on 2011-10-10. Retrieved 2009-09-09.
  8. ↑ "Mega Drive/Genesis Sound Engine List - GDRI :: Game Developer Research Institute". gdri.smspower.org.
  9. ↑ "SMPS - Sega Retro". segaretro.org. 23 January 2019.
  10. ↑ "Valley Bell's SMPS Research". Sonic and Sega Retro Message Board.
  11. ↑ "Sonic Hacking Utilities - Sonic Retro". info.sonicretro.org.
  12. ↑ "Steam Workshop :: SEGA Mega Drive & Genesis Classics". steamcommunity.com.
  13. ↑ "Pokemon Rom Hacks". InverseGamer.com. 20 September 2020. Retrieved 31 March 2021.
  14. ↑ "New patching format, UPS, debuts today". www.romhacking.net. 27 September 2023.
  15. ↑ "The PokéCommunity Forums - View Profile: HackMew". www.pokecommunity.com.
  16. ↑ "Newest patching format, APS, recently released". www.pokecommunity.com.
  17. ↑ Yin-Poole, Wesley (April 29, 2016). "Modders are already having fun with Sega Mega Drive classics on Steam". Eurogamer . Retrieved May 3, 2016.
  18. ↑ "Basic NES Reproduction".
  19. ↑ "World of Spectrum - Forced Redirect". www.worldofspectrum.org.
  20. ↑ "World of Spectrum - Forced Redirect". www.worldofspectrum.org.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.