MK8-online

MK8-online

Prepare once. Race natively. Connect with friends.

Created and maintained by RatOne

English · Português (Brasil)

An experimental Mario Kart 8 Deluxe 4.0.1 static recompilation project for Windows, with a native launcher, a Vulkan runtime and multiplayer rooms under development.

Download / Releases · Report an issue · Roadmap

On the starting grid

These are observed milestones, not a percentage-complete estimate. gameplay_verified remains false until the complete qualification passes. Detailed evidence and limitations: technical status and roadmap (Portuguese).

What this project does

The pipeline translates the supported game's AArch64 executable to C and compiles it for Windows x64. A C/C++ runtime supplies graphics, audio, input and system services; the Rust/Tauri launcher manages preparation, builds, updates and rooms.

RatOne develops and maintains the MK8 adaptation, launcher and integration. The translation/runtime foundation comes from SMM2Recomp and LASRecomp, with additional credited work from other projects. See third-party sources and licenses.

Get on track

Requirements

• Windows x64 and WebView2. Tools setup provisions a private Python 3.12 x64 automatically.
• A GPU and working graphics driver exposing Vulkan 1.3 or newer. Vulkan 1.2 is rejected at startup; API version alone does not qualify all required features or performance. A general minimum CPU/GPU specification has not been qualified.
• Your own base game, 4.0.1 update and prod.keys from your console, or a supported extracted game folder.
• About 28 GiB free for extraction/preparation, including a 4 GiB safety reserve. Keep additional space for source packages, tools and build caches. An SSD is recommended for preparation.
• Internet for the initial tool download (about 0.4 GiB installed, before build caches) and updates. Tools are shared across launcher versions.

Tools downloads a pinned CPython package, verifies SHA-256 and creates its local environment without changing system Python or PATH. Incompatible or incomplete environments are preserved in local/python-backup-* and recreated automatically. Available in 0.1.7; users of 0.1.6 can update through Support before retrying Tools.

Included in the 0.1.8 test release: readiness checks now use the private Python environment; package installation ignores external pip settings and requires verified binary wheels. Damaged download archives are fetched again, and invalid compilation-cache metadata triggers recovery instead of aborting preparation. These fixes require updating from 0.1.7 to 0.1.8. See technical status.

Additional recovery checks cover interrupted generation receipts and missing/invalid prepared-runtime hashes: derived files are regenerated from verified sources rather than trusted without evidence. Preparation checks the 4 GiB reserve before import/runtime replacement and reports unavailable destination volumes. Launcher tool processes ignore external Python startup variables while preserving their local script imports.

Version 0.1.8 fixes also distinguish inaccessible files from corrupt caches: a sharing or permission error stops preparation without treating the affected import/runtime as disposable. File replacement preserves the previous destination until the new file can be published. Missing or unreadable mirror sources stop pruning; failed download publication preserves the downloaded file and reports the local problem. Resolve the lock/access issue or reconnect the same drive before retrying. No permissions or antivirus settings are changed automatically.

The source preparation now includes the pinned vulkan-1.dll loader next to the game and retains it during dependency cleanup. SDL loads this DLL dynamically, so scanning static imports alone missed it in 0.1.7. A compatible Vulkan 1.3 graphics driver is still required; bundling the loader does not install a GPU driver.

Version 0.1.8 also adds operation locks between launchers sharing data/tools and between pipeline runs sharing a data folder. Failed cancellation keeps the process tracked so cancellation can be retried. Cleanup rejects linked parent directories and stops on permission errors instead of forcing deletion. These protections are still under validation; see the remaining limitations in the technical status.

The 0.1.8 launcher supervises processes separately: closing or losing the launcher stops its tool/build processes, while a running game keeps its locks and can finish saving normally. Other instances cannot start another game with the same saves, rebuild, change paths or start an update against those resources. Games using separate data folders can share read-only tools. Closing the launcher still disconnects its multiplayer gateway; this does not provide session reconnection.

Install and play

1. Download MK8-online-<version>-setup.exe from Releases. Choose the application and data folders. Installation is per user, without administrator privileges.
2. Open Install in the launcher. Complete Tools, then select the base game and update in Game files. The launcher can find keys alongside the game; select your own key file if necessary. It stores the path.
3. Run Build the game, wait for completion, then choose Play solo. Progress, elapsed time and the build log are available during preparation.

Language: both the launcher and installer offer English and Português (Brasil) through the Language / Idioma selector. First launch follows your system/browser language, with English as the fallback. Your choice is saved in the data folder and survives restarts. This changes the launcher UI; the game's language is independent. Tool logs and external diagnostic details retain their original language.

An extracted folder must contain exefs, romfs and control.nacp (or control/control.nacp); select I already have an extracted game folder. The active profile is 4.0.1 AArch64. Other game versions, DLC and XCI/XCZ import still need validation.

The setup includes the prebuilt host runtime and a minimal FFmpeg for videos; the game code is compiled on your PC. Incomplete extraction/preparation is repaired on the next build. Data defaults to %LOCALAPPDATA%\MK8-online and is preserved across updates and uninstalling. To select another drive when starting the portable launcher:

& .\Launcher.exe --data-dir E:\MK8-Local

Reuse the same data folder on subsequent launches. Older per-version data folders are not automatically migrated or deleted.

Updates: Support → Check for updates checks GitHub Releases, including prereleases. Update now downloads the setup, verifies its published SHA-256 and restarts the launcher after installation.

Race with friends

LAN rooms

Each PC needs its own prepared copy of the same game version. In Multiplayer, set your display name, create or discover a room and generate New invitation for each friend. Guests paste their individual invitations into the launcher. Invitations contain the host address: share them privately.

LAN discovery and traffic use UDP 47820 and depend on the network/firewall. The launcher selects the local address automatically; Alternative address supports a configured VPN or forwarded address. Esc → Salas com amigos opens the launcher's room tab from compatible runtime builds.

After joining in the launcher:

1. Everyone selects Play in room.
2. At the game's main menu, hold L + R and click the left stick to reveal LAN Play.
3. The host selects Create Room; guests choose the host in Lobby.
4. Choose characters and karts; the host sets the race rules.

The game supports up to 12 LAN players. Our transport tests cover 12 clients, but actual racing has only been tested with two game instances on one machine. Split-screen, two-PC play and full rooms need separate validation. Use Multiplayer → How to test on two PCs for the test procedure.

Internet room codes

A launcher configured with a public relay can create a new MK8-… code for each internet room. Friends paste that code to obtain their own connection credentials. The host controls the game room; the relay forwards packets. Players make outbound connections, while the relay operator exposes the server ports.

A public relay must be deployed and configured. The current tests used a local relay; they do not establish internet connectivity or low latency. Relay location and each player's connection affect the result. The game's official Online Play and local wireless (ldn) are not part of this LAN integration.

cargo build --release --locked -p mk8-session --bin mk8-relay
mk8-relay 127.0.0.1:47819 0.0.0.0 PUBLIC_RELAY_IP 47820

Nextendo: a future direction

Investigating Nextendo Network is on the roadmap for an alternative online service. There is no Nextendo integration in this build. Its account, friends and matchmaking services would require compatibility work and validation in this native runtime. This is a development intention, with no release date or affiliation implied; it does not replace the current LAN/relay path.

Performance, with context

The latest local candidate completed all four Mushroom Cup tracks and returned to cup selection in an 18 min 19 s run. On a Xeon E5-2666 v3 / 16 GB RAM / RX 580 2048SP, selected race sections measured:

These measurements exclude capture windows and do not guarantee 60 FPS throughout every scene or on other PCs. First-use shaders may still stutter or temporarily omit effects while compilation completes.

Recent changes fix command-list references surviving buffer/pool finalization and use preferred 128 MiB VMA allocation blocks. VRAM still grows between tracks: heap 0 reserved memory peaked at 1,648 MiB and remained reserved after returning to the menu. That figure is an allocator measurement, not total Windows GPU memory use; the isolated benefit of smaller blocks is still unproven. Direct image release remains experimental and disabled by default. See measurements and remaining investigations.

Help improve the next lap

In Support → Create report, create a diagnostic ZIP and attach it to an issue, with your CPU/GPU, launcher version, track/mode, steps to reproduce and expected result. For multiplayer, include reports from both PCs and describe the network setup.

Reports include game/build/tool logs and the build manifest. The launcher redacts personal paths and account names and excludes saves and keys; review attachments before sharing. Reports are stored in <data folder>\data\reports; a report is also created automatically after a game crash. Never post ROMs, console keys or private invitations.

Current priorities are repeated-cup VRAM stability, shader/frame-time consistency, visual fidelity, split-screen input and multiplayer on separate machines. Mii models are not integrated into gameplay; the current launcher does not expose a profile editor. Full qualification must cover image, audio, physical controls, clock speed and restart/save together.

Build and contribute

Development needs Rust, Python 3.12 x64, PowerShell 7 and .NET 10 x64 for the importer. Disk-type detection is optional: Windows storage drivers may report an unknown type, including on CI virtual disks. Start from the repository root:

.\scripts\start-launcher.ps1

The script downloads the pinned upstream sources, verifies their hashes, builds the launcher and opens it. Prepare your game through the same launcher workflow. To package the portable launcher:

python scripts/package-launcher.py

Output: target/portable/Launcher.exe. Full packaging prerequisites and release checks are in RELEASING.md. Keep adaptations in runtime/mk8 and toolchain; preparation applies them to a verified build copy. Do not edit upstream snapshots or generated game code directly. Follow AGENTS.md and run the tests for the changed area.

Credits and license

MK8-online is created and maintained by RatOne. Upstream authors retain credit and ownership of their contributions. Attribution and dependency notices are collected in THIRD_PARTY.md and docs/licenses.

Project code is licensed under GPL-3.0-or-later. Dependencies retain their own licenses; the SMM2Recomp snapshot includes GPLv3, while LASRecomp includes MIT notices. The combined project cannot simply be relabeled MIT. The license does not grant rights to Nintendo's game code, assets or trademarks.

An independent community project, not affiliated with or endorsed by Nintendo. Mario Kart and related names belong to their respective owners.