[!NOTE] A special thank you to Thomu, Moro, and JMOTZU for their extensive playtesting in the Co-op mod. Also, a special thank you to Thomu for his generous support towards the project's development.

Read more about it here

Mega Man X4 Recompiled

Fan-subtitled Japanese FMVs: one optional Japanese FMVs mod with a subtitle dropdown from acediez/Hondoori (English) and El Retro Dan (Spanish), with full attribution and preserved upstream readmes.

X and Zero. Together.

Mega Man X4 on Windows and Linux. 1.0.27 Stable Public Beta, with two-player co-op. Bring a friend through X's or Zero's campaign, on one computer or over netplay.

Downloads · What's new in 1.0.27 · Known issues

<p align="center"> <img src="docs/images/coop-jungle.png" width="640" alt="X and Zero together at the Jungle waterfall, with vertically stacked lifebars"> </p>

Two heroes, one campaign

Play X and Zero simultaneously, with their own attacks, voices and effects. Player 1 owns the story, boss clears and permanent progress; Player 2 joins as the other hero. Arrive together, tackle bosses together, and share team retries. The hero who lands a boss's final hit gets their victory theme.

Make it your co-op run	Choices
Play together	Local co-op with two controllers or separate keyboard bindings; two-player netplay from the launcher.
Pick your view	Unified camera by default. Split gives each netplay player an independent screen. Local co-op also offers side by side 8:3, with two 4:3 views in one window.
Arrange your HUD	Stacked lifebars by default, or side by side. Independent screens show their own player's meter.
Expand stage select	The experimental Co-op Stage Select Cast mod adds both heroes and their story companions. Off by default; P1's characters stay in front on both screens.
Manage your supplies	Either player opens both heroes' own pause menus. Choose weapons and manage supplies independently; either player resumes both. E-tank energy is separate while independent menus are enabled, and healing blocks unpause while your partner can keep navigating.
Set the door rule	Either player opens boss doors by default. Optionally wait for both living, present players.
Fight both story bosses	Opt into Double and Iris in sequence; return to the inner door for the second fight.
Turn up the challenge	Optional double effective boss health and shorter hit cooldowns, with separate timers for each player or one shared timer. Scaling also reduces Zero's boss damage by 20%.
Enable the secret codes	Ultimate Armor X's code and Black Zero can be enabled together. X still needs a capsule for the armor.

The extra boss encounters, scaling and character codes are off by default. The netplay host chooses the shared options.

<p align="center"> <img src="docs/images/split-x.png" width="48%" alt="Player 1's independent view follows X in a lower Jungle passage"> <img src="docs/images/split-zero.png" width="48%" alt="Player 2's independent view follows Zero near a different waterfall"> <br><em>One shared world, two independent netplay views.</em> </p> <p align="center"> <img src="docs/images/double.png" width="48%" alt="X and Zero face Double"> <img src="docs/images/iris.png" width="48%" alt="X and Zero face Iris in the optional second encounter"> <br><em>Double and Iris in one co-op run, when you enable the option.</em> </p>

Start playing

1. Download the Windows x64 ZIP and extract it, or use the Linux x86_64 AppImage (glibc 2.38 or newer).
2. Select your own original, unmodified Mega Man X4 USA (SLUS-00561) disc image. Choose the .cue from a .cue + .bin set. OpenBIOS is included; a separate BIOS dump is optional.
3. For local co-op, enable Mods → X + Zero Co-op, assign Player 1 and Player 2 in Controls, and choose Local co-op display for Unified or side by side 8:3, then press Play. For netplay, press Netplay and host or join using X + Zero Co-op. Both peers need the same release.

Only the verified original USA disc is accepted, including when every mod is disabled. All changes belong in Mods. Patched discs, undubs and retranslated disc images are unsupported; use the corresponding mods over the original disc.

Co-op requires OpenGL and takes effect on a fresh game boot. Single-player remains available.

With side by side 8:3 or Split netplay, each player sees their own character's weapon or technique award, including its artwork and instructions. P1 advances the shared award and Save/Continue flow; both heroes share the campaign's unlocks. Unified uses P1's award screen.

Fast loading is built in. The old CD Speed and Fast Loading mods are retired; the game now keeps verified disc data in memory and feeds it through the original loading routines. Music and cutscenes retain their normal timing.

<p align="center"> <img src="docs/images/netplay.png" width="720" alt="The launcher offers LAN / Direct IP and Online Netplay"> </p>

Offline co-op also supports save states (F7) and rewind (F8) when enabled. The Mods page includes widescreen, character codes and optional input display and diagnostic recording, off by default. Controls, saves and reporting guide →

Optional language mods offer Spanish and Brazilian Portuguese dialogue using the game's own font. Supply your Japanese Rockman X4 disc to choose Japanese movies, voices and the title screen independently. Translations are drafts awaiting native-speaker review. Language setup and scope →

Complete Story is an optional local solo/co-op mod, off by default. Add Zero's playable Memorial Hall duel, fight both Double and Iris, and watch the additional Colonel, Iris and Zero/Sigma movies in your campaign. Complete Story setup and scope →

<details> <summary>See the co-op settings</summary> <p><img src="docs/images/coop-options.png" width="800" alt="Co-op settings in the shipped launcher"></p> </details>

Help improve the public beta

Expect bugs; independent cameras can still slow down. Online sign-in/startup reports remain under investigation. Check the burndown or report a bug.

To record a bug, enable Playtest Diagnostics → Input Display and Recording before local play. For netplay, the host enables X + Zero Co-op → Netplay diagnostic recording for both peers. Both recording options default off. Reproduce the problem, quit normally, and zip saves/diagnostics beside the executable or AppImage. Include a video and the release version; for netplay, collect both computers' logs. These recordings include starting game saves. Details →

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Built with PSXRecomp and recomp-ui. Build and contribute · R.A.I.D. community

Original project code is MIT licensed. Dependencies retain their own licenses and notices. Mega Man X4 and the game imagery belong to Capcom. You supply the game disc; this is an unofficial project.

Building player releases

Run the maintained shared command from this repository root:

psxrecomp-v4/tools/package_title_release.ps1 --channel public --platform windows --jobs 2

Use --channel playtest for diagnostics enabled by default, and --platform linux for an AppImage (WSL on Windows). --platform all prepares both platforms. The version comes from packaging/release/VERSION; artifacts and checksums go to dist/. --work-dir and --out-dir select owned build and artifact staging. The title wrappers accept these shared GNU-style arguments; old title-specific build/version/cache switches are replaced by the shared interface.

packaging/release.toml carries this title's payload. The shared builder owns regeneration, the fresh per-title selective PGO build/training phases, native OpenBIOS, launcher assets, notices, channel defaults and final archive checks. No old profile or private cache is reused. The original-disc inventory found no separate executable overlay. The resident boot program is regenerated; eligible uncovered code uses the bundled overlay toolchain. No private or unqualified cache is shipped.

The command does not publish or upload. Build/package success does not replace the release's gameplay or owner acceptance checks. See the framework's docs/RELEASING_A_TITLE.md for the shared command and verification contract.