MVC1 CROSS FEVER — FOUR-PLAYER V2.1 PREVIEW

This package repairs installation and supplies MVC1's matching four-controller
core. Game code, persistent 1P/2P/3P/4P/COM markers and the v2 artwork are retained.
It is separate from DHC and from XMvsSF 3v3 + DHC.

ONE INSTALLATION PATH

1. Extract the package for your system into a new folder you can write to.
   Windows 10/11 x64 uses the .dll; macOS 26+ on Apple silicon uses the .dylib; Linux x64
   (Ubuntu 22.04 or compatible runtime) uses the .so. Use an existing matching
   64-bit RetroArch installation; RetroArch itself is not included.
2. Supply your clean MVC1 Europe 980123 parent, including its original mvsc.key.
   A valid merged archive is accepted: each required root member is verified by
   name, size and SHA-256. Regional clone files and other extra members remain
   in your original archive and are left out of the new game. No manual repack
   or guessed deletion is needed. A USA/Asia clone alone is not the Euro parent.
3. Windows: drag that ZIP onto BUILD.cmd. No Python or compiler is needed.
   macOS/Linux: run python3 install.py /path/to/your/mvsc.zip in this folder.
   Both create output/mvsc4p.zip and its receipt without altering your input.
   Existing outputs are refused; extract into a new folder to build again.
   Python installation requires a filesystem supporting hard links, such as
   APFS, ext4 or NTFS. Use an internal supported disk rather than exFAT/FAT
   or a network share; the verified result can be copied afterwards.
4. Windows: run PLAY.cmd and give the path to your retroarch.exe when asked.
   macOS/Linux: in RetroArch choose Load Core, select this package's
   fbneo_mvc1cf_libretro.dylib/.so, then Load Content → output/mvsc4p.zip.
   The core identifies itself as FinalBurn Neo (MVC1 Cross Fever 4P).
   A stock FBNeo/Fightcade/MAME 2003 Plus core is not this four-port profile.

The standalone MVC1-Cross-Fever-v2.1-preview.cmd is also a patch-only installer.
It accepts the original optional-key 20-member format, but the bundled RetroArch
setup requires the full 21-member parent because its core needs your real key.
Neither an empty key nor a renamed key from another region is a substitute.

CONTROLLERS

Assign four RetroPads with separate Device Index values under Settings → Input.
Ports 1 and 3 form the left team; ports 2 and 4 form the right team. Each fighter
keeps its own controller during Duo. Avoid remaps that share one physical pad
between ports. Check Quick Menu → Controls for this content after loading it.

Default RetroPad buttons (you may bind your physical arcade buttons to these):
    Y = LP     X = MP     L = HP
    B = LK     A = MK     R = HK

HP+HK from attract/selection joins that controller. Release the chord before
confirming with an attack button. P1/P2 choose the first fighters; P3/P4 choose
the partners. The game runs in free play: Start and Select/Coin have no game
input in this profile. The original board's Start/Coin lines carry MK/HK, so
adding stock Start/Coin bindings causes the reported Start-as-kick confusion.
RetroArch's own menu/hotkeys remain frontend controls.

    HP+HK               Tag to the living partner
    QCF+HP+HK           Native Team Hyper
    QCB+HP+HK           Duo / Variable Cross (at least two bars; spends gauge)

QCF = quarter-circle forward; QCB = quarter-circle back.
Use fresh boot/selection; automatically loaded or older save states can skip
the ROM's join and ownership initialization. The Windows launcher disables
automatic state loading for this launch and preserves the user's pad bindings.

NETWORKING AND COMMUNITY ACCEPTANCE

This is a local four-player community preview. A matched-build four-person
network session has not been accepted; Fightcade's stock two-player room is not
a supported four-player host/join path. For an experimental RetroArch session,
every participant must have identical package, core and generated member hashes;
report the frontend version and assigned ports. Do not treat another game's
successful netplay session as MVC1 validation.

Experimental host/join checklist (UNVERIFIED for this MVC1 preview): the host
chooses Netplay → Start Hosting, then loads this exact core/game. Other players
choose Netplay → Refresh and join that room, loading the same core/game if
prompted. Use the same RetroArch version, confirm that the connection assigns
four different player ports, then check the 1P/2P/3P/4P markers with independent
movement. Stop the session if ownership, hashes or synchronization differ.
The frontend's generic host/join flow is documented at
https://docs.libretro.com/guides/netplay-getting-started/ ; this package does not
claim a successful four-person session or Fightcade/GGPO support.

Tests and their exact limits are in TEST_RESULTS.json. The new installer was
exercised in Python and the actual generated PowerShell body on macOS; native
Windows PowerShell 5.1/CMD remains a community check. Simulated RetroPad tests
are distinguished from four physical pads. Full controller selection, tags,
Duo, KO replacement, rematch and CPU participation remain listed explicitly
where the new package has no fresh acceptance run. The old v2 MAME diagnostics
remain comparison evidence; they are not silently reclassified as new-core tests.
C.S's exact 48-file archive was not supplied; the 22/48-member installer controls
are declared test fixtures.

REPORT A RESULT

Include package/core version, operating system, four Device Index assignments,
generated receipt, and the exact failed action. Check each fighter's six attacks,
direction input, join/tag/Duo, KO replacement and rematch before reporting a
four-human pass. Physical four-pad and online acceptance will be updated from
community results after publication.

SOURCE AND CREDITS

The core is derived from libretro/FBNeo commit
aceeebed9e7edc8a28652365a064baee9a16e274. Its native four-controller declaration
is shared with XCOTA TAG and MVC_HARNESS; XCOTA also supplied the reference
patched-ROM loading and Windows cross-build approach. MVC1's ROM still owns
gameplay routing. The new mvsc4p driver leaves vanilla mvsc and other drivers
unchanged. All four controllers use the same stateless opposite-direction rule.
FBNeo's license, exact core/source pins and a corresponding source download
accompany this package. No game ROM, decryption key or save state is distributed.

RetroArch setup references:
https://docs.libretro.com/guides/input-and-controls/
https://docs.libretro.com/guides/cli-intro/
