XCOTA TAG v4 - RetroArch core (four players on one machine, online with Parsec or RetroArch netplay)
===================================================================================================

WHAT THIS IS

FinalBurn Neo's libretro core (the CPS-1 / CPS-2 part of it), built with three small changes:

  1. A four-player X-Men: Children of the Atom, "xmcota4p": four controllers, P1 + P3 against
     P2 + P4, for the XCOTA TAG four-player ROM.
  2. The XCOTA TAG patched sets (xmcota4p, xmcota, xmcotau, xmcotaj, xmcotar1d) load by file name,
     although their checksums differ from the stock game on purpose.
  3. RetroArch lists it as "Arcade (FinalBurn Neo - XCOTA TAG)".

The changes are in src/xcota_core.patch. No ROMs are included: you patch your own copy of the game
with the XCOTA TAG installer.

FILES

  fbneo_xcota_libretro.dll    the core for Windows (64-bit)
  fbneo_xcota_libretro.so     the core for Linux (64-bit)
  fbneo_xcota_libretro.info   its RetroArch info file
  src/                        the source patch, the patcher, and build_core.sh (macOS builds from here)
  FBNEO_LICENSE.txt           FinalBurn Neo's licence, which applies to this core

SET IT UP

  1. Install RetroArch (retroarch.com).
  2. Copy the core into RetroArch's "cores" folder and the .info file into its "info" folder.
     Settings > Directory shows where both are.
  3. Make the four-player ROM: run the XCOTA TAG v4 four-player installer on your own xmcota.zip.
     It writes xmcota4p.zip. Put that file in any folder you keep ROMs in.
  4. In RetroArch: Load Core > "Arcade (FinalBurn Neo - XCOTA TAG)", then Load Content > xmcota4p.zip.

  macOS: open Terminal in the src folder and run  sh build_core.sh  (needs Xcode's command line
  tools: xcode-select --install). It downloads FinalBurn Neo at the pinned commit, applies the patch
  and builds fbneo_xcota_libretro.dylib.

CONTROLLERS

  Settings > Input > RetroPad Binds > Port 1 / 2 / 3 / 4 Controls > Device Index: pick a pad for
  each port. Ports 1 and 3 are one team, ports 2 and 4 the other.

  RetroPad      arcade button
  Y             light punch (LP)
  X             medium punch (MP)
  L             heavy punch (HP)
  B             light kick (LK)
  A             medium kick (MK)
  R             heavy kick (HK)
  L2            LP + MP + HP
  R2            LK + MK + HK

  There are no coins. HP + HK joins a game (free play). In a fight HP + HK tags.
  Each player owns one X-Man. The team's first pick is P1's (or P2's), the second is P3's (or P4's),
  and each fighter answers to its owner's pad wherever it is: on point, in a duo, after a tag.

FOUR PLAYERS ONLINE WITH PARSEC

  1. The host sets up RetroArch as above and shares the screen with Parsec.
  2. The three guests connect with Parsec and plug in their pads. Parsec gives each guest a pad on
     the host's computer.
  3. On the host: Port 1 Controls = the host's pad, Ports 2, 3 and 4 = the guests' pads.
     Main Menu > Configuration File > Save Current Configuration keeps it.
  4. For the least delay: the host on a wired connection, RetroArch in fullscreen with Vsync on.

FOUR PLAYERS WITH RETROARCH NETPLAY (everyone runs RetroArch)

  Everyone needs this same core and the same xmcota4p.zip. The installer makes the same file from
  the same source set, so everyone can make their own.
  Before joining, each player picks their port: Settings > User Interface > Show Advanced Settings
  on, then Settings > Network > Request Device 1..4: YES for your own port only (P1 port 1, P3
  port 3 ...). Host: Main Menu > Netplay > Host. Players: Netplay > Refresh Netplay Host List (or
  Connect to Netplay Host) and join. RetroArch netplay takes up to 16 players.

TWO PLAYERS AND OTHER EMULATORS

  Fightcade 2       The two-player v4 installer's output goes in Fightcade's FBNeo ROM folder
                    as xmcota.zip. Both players need the same file.
  Stock FBNeo core  Put the two-player xmcota.zip in RetroArch's system/fbneo/patched/ folder and
                    turn on "Allow patched romsets" in the core options.
  MAME              MAME's menu refuses patched sets ("required ROM images are missing or
                    incorrect"). Start it from a command prompt instead:
                        mame xmcota -rompath "C:\path\to\roms"
                    It warns about checksums and runs. MAME also needs qsound_hle.zip in the
                    ROM folder.
  Four players only run on this core (or on a CPS-2 board wired for four).

WHAT WAS TESTED (diagnostic runs, September 2026)

  Linux core: loads xmcota4p.zip. On every port all six buttons and four directions reach the game,
  with no cross-talk between ports. A four-player take played through: four joins, four picks, a
  tag, P3 and P4 moving their own X-Men.
  Windows core: built, its exports and imports checked. Not yet run on Windows.

LICENCE

  FinalBurn Neo's licence applies (FBNEO_LICENSE.txt): free and non-commercial. The source changes
  are public in src/.
