Change the Emulator for One Game in KNULLI

Safety and Limits

This guide changes the per-game Emulator selection for one game only. It does not recommend a “best” emulator, change an entire system, repair a ROM or BIOS, identify the runtime binary visually, or prove performance or compatibility.

Alternatives can use different save locations, state formats, controls, configuration, menus, and achievement behavior. Record the exact current value first. Avoid irreplaceable progress and do not create or overwrite a valuable save state merely to test an alternative.

Make one change at a time. If the game fails or behaves unexpectedly, exit normally and restore the exact recorded value. Choose AUTO only when the original value was AUTO or otherwise inherited.

Short Answer

To change the emulator for one already-visible, already-launching game:

Record its exact current Emulator value.
Highlight the game and hold the face button that normally launches it.
Open Advanced Game Options.
Open Emulator.
Choose one alternative shown in the installed list.
Back out normally.
Reopen Advanced Game Options and confirm the selected value remains visible.
Launch the same game once and exit normally.
Reopen the menu and confirm the same value remains.
Restore the exact original value. Use AUTO only if that was the original/inherited state.
Reopen the menu once more to confirm rollback.

This proves that KNULLI recorded a per-game selection and handed the launch to an accepted configuration. It does not prove which binary ran, that the choice is optimal, or that saves and states are portable.

For broader setup routing, use the KNULLI troubleshooting and setup hub.

Scope and Prerequisites

Evidence and version scope

Device: RG CubeXX / H700 KNULLI builds

Releases: Firefly 20241204, Gladiator II 20250813, Scarab 20260511

Start: one game is visible and already launches with its current inherited/default or explicit value

End: one listed alternative persists through menu reopen and one launch/normal exit, then the exact prior value is restored and rechecked

Evidence: official KNULLI documentation, frontend source, and tagged launch/system source; no owner test

Do not use this guide if the game is missing, already fails to launch, already displays a BIOS warning, or the actual problem is Quick Menu access.

If the game is not visible, stop and use KNULLI Games Not Showing Up. If an explicit BIOS warning appears, use the KNULLI Missing BIOS guide.

If progress is valuable, back up KNULLI saves and personal data before experimenting. Do not rely on a save state as the only rollback.

Release Matrix

Release	UI evidence	Launch behavior	Caveat
Firefly `20241204`	Date-bounded official frontend source shows Advanced Game Options, Emulator, and `AUTO`.	Tagged launcher accepts emulator/core values and chooses the corresponding generator.	The tagged package used a moving frontend branch; the cited pre-release commit is not cryptographic proof of the exact binary commit.
Gladiator II `20250813`	Date-bounded source shows the same field and `AUTO`.	Tagged launcher uses the selected combination.	Available values can differ from Firefly and Scarab.
Scarab `20260511`	Pinned frontend commit confirms the field and `AUTO`.	Tagged launcher follows the same selection path.	Installed choices still depend on system/build definitions.

This is shared KNULLI frontend/config-generator behavior, not an RG CubeXX performance claim.

Understand AUTO, Explicit Values, and the Installed List

AUTO

FACT: KNULLI has global, system, and per-game layers. AUTO removes the per-game override and inherits the effective selection from the next layer above.

AUTO does not mean one universal emulator. Its effective result can change if a higher layer changes.

Explicit value

An explicit value in the per-game Emulator field applies to that game only. It does not change every game in the system.

The visible field is Emulator. A listed value may represent a standalone emulator or an emulator/core combination. Do not assume every system or release provides a universal separate Core selector.

Installed list

SOURCE-CONFIRMED: The selector is populated from combinations included for that system and installed build. Choices can differ by system, architecture, and release.

Choose only a value shown in the installed menu. Do not copy a list from another device, system, guide, or release.

If only AUTO appears, stop and leave it unchanged.

What remains unconfirmed

UNCONFIRMED: cross-emulator save/state portability, better speed, lower latency, higher accuracy, improved compatibility, or identical runtime features. A successful launch establishes none of these.

Record the Before-State

Confirm the game already launches.
Exit normally.
Record the exact KNULLI release.
Highlight the game.
Hold the face button that normally launches it.
Open Advanced Game Options.
Read and record the exact Emulator value.

The physical confirm/launch button can be south or east depending on GUI settings. Use whichever button normally launches the highlighted game; do not hard-code a letter from another layout.

The original value may be AUTO or an explicit listed choice. Do not assume AUTO. Exact rollback depends on this record.

Choose One Listed Alternative

Open Advanced Game Options → Emulator.
Read only the choices shown by the installed build.
If no alternative appears beyond AUTO, close the menu and stop.
Select one listed alternative.
Change no other setting.
Back out normally.

Do not choose based on an unsupported “best emulator” claim. Do not use the change to mask a broken ROM, missing BIOS, discovery failure, or Quick Menu issue. Do not edit configuration files or select an unlisted engine.

Verify Selection Persistence Before Launch

Keep the same game highlighted.
Hold the normal launch button again.
Reopen Advanced Game Options.
Read Emulator.
Confirm it exactly matches the selected alternative.

If it returned to AUTO or another value, stop. Record the visible state. Do not edit batocera.conf, knulli.conf, gamelist.xml, generated RetroArch configuration, or emulator files.

The visible value proves that the frontend recorded the per-game selection at that moment.

Launch and Exit the Same Game Once

Launch the same game.
Confirm only that content starts and basic input permits a normal exit.
Do not benchmark performance.
Do not create, overwrite, or load a valuable state.
Do not use Quick Menu as proof of exact core identity.
Exit normally.

KNULLI generates launch configuration from EmulationStation settings and passes the selected emulator/core values to its launcher. A successful launch shows that KNULLI accepted the configuration and started content.

Gameplay alone does not prove which binary/core ran, whether the choice is faster or more accurate, or whether saves are compatible.

Verify Persistence After Launch

Reopen Advanced Game Options → Emulator for the same game and confirm the same alternative remains visible.

This is the forward-change endpoint: the UI value persisted through one close/reopen and one launch/exit. It says nothing about other games.

Restore the Exact Original Value

Rollback is part of the procedure:

Open the Emulator selector.
If the recorded original value was explicit, restore that exact value.
If the original value was AUTO or inherited, select AUTO.
Back out normally.
Reopen Advanced Game Options.
Confirm the exact original value is visible.

Do not blindly choose AUTO when a pre-existing explicit override was recorded. That would change the prior configuration instead of restoring it.

If needed, launch and exit once more only to confirm the restored path starts. This does not extend the proof beyond one game’s frontend selection and launch handoff.

Libretro and Standalone Expectations

KNULLI distinguishes libretro/RetroArch cores from standalone emulators.

A libretro choice uses RetroArch and can expose RetroArch-only features such as Quick Menu.
A standalone choice does not provide RetroArch Quick Menu and can use different configuration, controls, save paths, and menus.

If Quick Menu disappears after selecting standalone, that is not automatically an M+B fault. Restore the prior value if RetroArch features are required.

If a confirmed libretro selection is active and Quick Menu still will not open, use fix KNULLI Quick Menu and M+B access. Quick Menu visibility still does not prove exact core identity.

Stop and Handoff Branches

The game was not visible before the change

Stop. This workflow requires an existing visible game. Use the games-not-showing guide.

The game did not launch before the change

Stop and diagnose a visible game that still will not launch. Do not switch emulators to hide an existing content, BIOS, or setup failure.

Only AUTO appears

Stop and leave AUTO. Do not import lists or configuration from another release/device.

The alternative fails to launch

Restore the exact prior value. If an explicit BIOS warning appears, use the BIOS handoff. Do not download BIOS files, convert content, update/downgrade, or edit configuration here.

The alternative may be standalone. Restore the prior selection if RetroArch is required. Use the Quick Menu guide only after confirming a libretro choice.

Saves or states appear missing

Stop and restore the prior selection. Preserve data; do not move, delete, or convert saves/states here.

Controls differ

Restore the prior selection. Do not globally remap RG CubeXX built-in controls.

One game seems better or worse

Treat it as one game-specific observation. Do not convert it into a benchmark or recommendation.

Version Differences

Firefly `20241204`

The official frontend branch immediately before release shows Advanced Game Options, Emulator, and AUTO. Its tagged distribution used a moving frontend branch, so source attribution is date-bounded. Do not infer installed choices from later releases.

Gladiator II `20250813`

The official pre-release frontend branch shows the same field and AUTO inheritance. Tagged launcher behavior supports the handoff; installed alternatives can differ from Firefly and Scarab.

Scarab `20260511`

The release pins frontend commit 4041b56, which confirms the menu path and AUTO entry. Tagged definitions can add or remove choices relative to older releases.

What this guide does not cover

This guide changes one visible game’s emulator with an exact rollback to AUTO. It does not fix a missing game, place BIOS files, repair a title that never reached the eligibility baseline, configure networks or storage, remap controls, or change global emulator defaults. If the title remains visible but will not launch, use the visible-game launch-failure guide.

Screenshot, Privacy, and Evidence Limits

Optional images may show one cropped game, the before-value, installed selector, selected value before/after launch, and the restored value.

Redact ROM filenames, complete libraries, BIOS names/hashes, save/state filenames, accounts, RetroAchievements names, network details, and personal overlays.

A selector screenshot proves an option was offered, not that it is suitable. A title/gameplay screen proves display, not runtime identity or performance. Quick Menu proves libretro, not the exact core. One rollback proves only that one game’s frontend value returned.

FAQ

Does this change every game in the system?

No. This is a per-game setting.

What does AUTO mean?

AUTO removes the per-game override and inherits the next effective setting layer. It is not one universal emulator.

Why do I see only AUTO?

That installed system/build exposes no alternative through this menu. Stop and leave it unchanged.

Where is the separate Core selector?

Do not assume one exists universally. The visible field is Emulator, and its entries can encode an emulator or emulator/core combination.

Which emulator is best?

This guide makes no recommendation. A defensible comparison needs game-, device-, release-, and version-specific evidence.

Will my saves and states work after switching?

Do not assume so. Back up valuable progress, avoid valuable-state tests, and restore the prior selection if data appears missing.

Does a successful launch prove which core ran?

No. It proves the configured launch path displayed content. Gameplay is not reliable binary/core identification.

Should rollback always use AUTO?

No. Restore the exact prior value. Use AUTO only if the original state was AUTO/inherited.

Safety and Limits