One of the most popular sites dedicated to ROM hacking of video games was ROMhacking.net, which first went online in late 2005.
From its inception up until 2024, it served as a hub related to all things ROM hacking, hosting a repository of hacks, translations, utilities, documents, and patches for many well-known and obscure video games from the third generation up to the seventh generation.
ROMhacking.com was the immediate predecessor of ROMhacking.net, which launched five years earlier in 2000 and was briefly renamed as ROMhacking.org between 2001 and 2002 before returning to its original name afterwards and then went offline in late 2004.
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.
store graphics in tiles, which are 8x8-pixel units of data, which are arranged on-screen to produce the desired result.
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 with Generation I-V Pokémon games[9]), to full-blown thematic changes (usually with accompanying palette changes; see below).
A core component of many hacks (especially of role-playing video games) is editing data such as character, item, and enemy properties.
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, usually within the limitations of the hardware and software of the gaming platform.
Exceptions exist, however, such as the most recent Super Mario World hacks where custom music can have new instruments not found in the original game.
A utility known as the N64 Midi Tool was created to edit the sequences that the majority of Nintendo 64 games use, however it does not cover first-party N64 titles that use a slightly different engine such as Super Mario 64.
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.
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.
[21] Compared to other patching formats, the APS system is more space efficient, is reversible, and is faster than its predecessor.
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.
The success of this game prompted Capcom to release Street Fighter II: Hyper Fighting as an official response.