W4ME Station

Run WASM-4 games on Java ME phones.

W4ME Station brings unmodified WebAssembly cartridges to CLDC 1.1 / MIDP 2.0 devices, including feature phones from the mid 2000s.

Thirteen bundled cartridges ship in a roughly 292 KiB JAR. The runtime uses no JIT, and the bundled library needs no network connection. Both release variants stay below 300 KiB.

Download

Variant	Application	Descriptor
Full, with optional JSR-75 file browsing	w4me-station.jar	w4me-station.jad
Base, without JSR-75 classes or permissions	w4me-station-base.jar	w4me-station-base.jad

Release notes and SHA-256 checksums are stored beside the versioned 1.1.0 artifacts.

W4ME Station targets CLDC 1.1 / MIDP 2.0 devices. It is independent from and not endorsed by the WASM-4 maintainers.

Cartridge library

#	Cartridge
1	Sokoban
2	Wasm Wars
3	Annoying Robots
4	Waternet
5	Dragon Poker Draw
6	Tic Tac Toe
7	Watris
8	Glowfish Chess
9	Duck Maze
10	Untangle
11	Nyan Cat
12	Sound Demo
13	Plasma Cube

Further .wasm files can be installed from the device.

Features

• validated WebAssembly execution with a persistent fixed-width W4IR cache;
• WASM-4 graphics, input, audio, disk, text, and tracing host APIs;
• thirteen bundled cartridges plus HTTP(S), RMS, URL, and optional JSR-75 loading;
• phone keys, keyboard controls, pointer input, and an on-screen touch pad;
• per-cartridge persistent disk storage with checksummed RMS generations;
• a native paused game menu with Continue, Save State, Load State, Settings, Restart Cart, and Exit actions;
• one temporary in-session Save State/Load State slot;
• device-dependent MMAPI audio with streamed MIDI, playTone, and silent fallbacks;
• global RMS-backed hard mute and master-volume controls;
• deterministic host, KEmulator, and optional phoneME verification.

The release version is 1.1.0. The verified scope and remaining limitations are documented in Compatibility.

Requirements

Development requires Linux with just and a docker command. Docker Engine works directly; Podman users can provide its Docker-compatible command. The project toolchain contains JDK 8, ProGuard, KEmulator, WABT, and supporting utilities. Version-sensitive components are pinned by the container definition.

just setup
just doctor

Java sources and classfiles remain pinned to Java 1.3.

Build

just build

Artifacts are written to dist/:

Artifact	Purpose
w4me-station.jar / .jad	full build with optional JSR-75 file browsing
w4me-station-base.jar / .jad	build without JSR-75 classes or permissions

Both variants contain the same thirteen cartridges. The base build works on MIDP 2.0 devices that do not implement the optional FileConnection API.

Installing on a phone

Download one matching .jad/.jar pair from the table above and keep both files in the same directory. Use the full build on devices with JSR-75 FileConnection support; use the base build if the full build is rejected or the device lacks that optional API.

Open the .jad from the phone's application manager or file manager. If the device does not accept JAD installation, transfer and open the matching .jar directly. Installation details and troubleshooting are covered in Installation.

Controls

Input	Player 1	Player 2
Movement	Arrow or directional phone keys	E, S, D, F
Button 1	X, Fire, or 5	Tab
Button 2	Z or 0	Q

Touchscreen devices display an on-screen directional pad and action buttons. The controls stay outside the 160×160 framebuffer whenever the screen is large enough.

The gameplay soft key opens the native LCDUI system menu at a completed frame boundary. Game updates, presentation timing, input, and audio advancement stay paused until play resumes. The menu provides Continue, Save State, Load State, Settings, Restart Cart, and Exit.

Sound settings is available from the cartridge library and the in-game command menu. It offers explicit WAV synthesis, MIDI synthesis, and Simple tones profiles, a hard global Sound On/Off mute, and master volume when the backend supports it. The form reports the active fallback when the selected technology is unavailable. Sound Off bypasses host audio bookkeeping, synthesis, Player work, and end-of-frame audio ticks. Confirmed settings persist across MIDlet restarts.

The in-game menu also provides one temporary Save State/Load State slot. It is replaced by the next save and is cleared when the cartridge is restarted, closed, or returned to the library. It is separate from persistent WASM-4 disk storage and does not survive a MIDlet restart.

On the tested Nokia E71, short sound effects work, but continuous music stutters. Audio timing and fidelity remain device-dependent; see Compatibility and Audio architecture and diagnostics.

Loading cartridges

The launcher includes the thirteen cartridges listed above, in that order.

Additional .wasm files can be installed from HTTP(S), entered as a file:// URL, or selected with the JSR-75 browser on supported devices. Installed cartridges are copied into RMS and can be relaunched without their original file or network source.

Cartridges are third-party works. Their authors, upstream sources, hashes, and licenses are listed in Third-party notices.

Verification

just fmt
just quality
just analysis
just security
just verify

just quality and just verify are the minimum local gates. Java production changes also run through Error Prone and SpotBugs with just analysis. Dependency, workflow, permission, release-tooling, and security changes use just security.

The main CI repeats strict analysis, security, correctness, release, and checked-in artifact checks. The weekly and manually triggered Nightly quality workflow adds external-link checks, Trivy scanning, a CycloneDX SBOM, and a reproducible-release comparison. Run the same deep gate locally with:

just nightly

The stable commands are listed by just --list. Specialized KEmulator, phoneME, and profiling commands are described in Development. Generated logs, screenshots, benchmark receipts, and audit reports are written under build/reports/.

Documentation

• Compatibility and limitations
• Installing on a phone
• 1.1.0 release notes
• Contributing
• Repository automation rules
• Security policy
• Development and testing
• Performance methodology
• Release checklist
• OpenSpec changes

License

W4ME Station source code is available under the MIT License. Bundled cartridges retain their own licenses and are not covered by the MIT License.

The optional local phoneME rig is GPL-2.0-only and is not distributed with the project. Its modified corresponding source is not public yet, so its binaries must remain local and ignored. See Performance.