ROM Hacks

ROM Hacks

Emutastic can apply an IPS, BPS, or UPS patch to a base ROM and add the result as its own game — without modifying or duplicating the original. The patch is applied to the ROM data in memory the moment you launch, so what's on disk stays a clean, untouched copy.

Applying a hack

1. Import the base ROM the hack was made for into your library as usual.
2. Right-click the game → Apply ROM Hack…
3. Pick the patch file (.ips, .bps, or .ups).
4. Give the hack a name.
5. It appears as a separate library entry alongside the original.

The patch you select is copied into Emutastic's data folder, so you can delete the original download afterward.

What you get

• Its own entry — the hack shows up next to the original, not in place of it. Both stay playable.
• Its own saves — the hacked entry gets a separate battery save and save states, so progress in the hack never touches the original game's saves.
• Original untouched — your base ROM file is never written to; the patch lives only in memory at launch. There's no second full copy of the ROM on disk — just the small patch file.

Supported patch formats

Format	Notes
BPS	Recommended. Stores a checksum of the source ROM, so a wrong or mismatched base ROM is caught and rejected before launch.
UPS	Also checksum-verified against the source ROM.
IPS	The classic format. Has no checksum, so it's applied as-is — a wrong base ROM (or a headered/unheadered mismatch) just produces a broken game rather than a clear error.

XDelta / VCDIFF patches are not supported.

Supported systems

ROM hacks work on cartridge systems — the ones whose cores load the ROM into memory:

NES, Famicom Disk System, SNES, Game Boy, Game Boy Color, Game Boy Advance, Nintendo 64, Genesis / Mega Drive, Sega 32X, Master System, Game Gear, SG-1000, TurboGrafx-16, Virtual Boy, Atari 2600, Atari 7800, Atari Jaguar, ColecoVision, Magnavox Odyssey².

Disc-based systems (PlayStation, Saturn, Sega CD, Dreamcast, PSP, GameCube, 3DS, Neo Geo CD, CD-i, 3DO) are not supported — their cores read the disc image by file path rather than from memory, and IPS/BPS/UPS are cartridge-ROM formats. The Apply ROM Hack option only appears on supported systems.

Matching the patch to the right ROM

A patch is built for one specific ROM. If the base ROM doesn't match, the hack won't work:

• BPS / UPS — Emutastic verifies the patch's stored source checksum against your ROM. If they don't match, you get a clear "this patch doesn't match this ROM" message and no entry is created. The usual causes are a different region, a different dump, or (on SNES) a headered vs. unheadered copy.
• IPS — no checksum to verify, so it's applied blindly. If the result is broken, it's almost always a region/revision mismatch or an SNES header mismatch. Prefer an unheadered ROM for SNES IPS patches (the modern standard).

Tip

Hack pages usually state which ROM version the patch expects (region, revision, headered/unheadered) — match it exactly. BPS is the most forgiving format to work with because it tells you immediately when the ROM is wrong.

Artwork & metadata

The hacked entry inherits the original game's developer, publisher, year, genre, and description (copied from the base game when you apply the patch). Box art starts blank — add your own from the detail card's ⋯ → Add Cover Art from File, or use Download Cover Art (it scrapes by the original game's name where it can).

If you instead import an already-patched ROM as a standalone file (rather than using Apply ROM Hack), it scrapes like any other ROM: by content hash first, then by filename. A pre-patched ROM's bytes won't hash-match anything, so it falls back to filename — name it close to the original and it'll pull the original's art and info.

Storage

• Patch files: [DataRoot]/RomPatches/{Console}/ (in portable mode, under PortableData/).
• The hack's link to its patch is stored in the library database, so the entry syncs with Cloud Sync — but the patch file and base ROM are not synced. On a second PC, re-apply the patch (or copy your RomPatches folder and base ROM across).
• Deleting a hacked entry from the library leaves the patch file in place (like artwork).

Limitations

• One patch per hacked entry. To stack multiple patches, apply them externally first and import the result as a pre-patched ROM.
• The base ROM must be a single cartridge-style file the core loads from memory. Multi-disc / disc-image hacks aren't supported.
• Emutastic applies existing patches — it isn't a tool for creating ROM hacks.