ktnes

NES EMULATOR

ktnes

ktnes — a multiplatform NES emulator written in Kotlin (source on GitHub). It targets Android, web (JavaScript) and native JVM/Kotlin/Native platforms and implements several common mappers (including Mapper 0, 1 and MMC3).

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ktnes emulator screenshot.

nesPRIMARY SYSTEM

2020PROJECT BEGAN

Open sourcePROJECT MODEL

WHY IT MATTERS

Why ktnes exists

ktnes is an experiment and practical implementation of an NES emulator using Kotlin Multiplatform. The project explores running the same emulator core on Android, in the browser (via a JavaScript target) and on native JVM/Kotlin/Native targets while keeping most of the code shared in Kotlin.

BEST FOR

Notable capabilities

Multiplatform Kotlin implementation with working CPU, PPU and APU components; audio (noted as still imperfect in the repository); support for several mappers including Mapper 0, Mapper 1 and Mapper 4 (MMC3). Project is published with an Apache 2.0 license and source, build scripts and platform-specific front ends are available in the official repository.

The people behind ktnes

History & status

The project is authored and maintained in the public GitHub repository felipecsl/ktnes. The repository README and license header reference 2020. The README states the project is "still under active development" and lists implemented mapper support and platform targets. The codebase provides Android, web (JavaScript) and shared library modules; CI and Gradle build files are present in the repository. There are community issues and occasional commits in the repository, indicating ongoing maintenance on the upstream repo rather than being an abandoned stub. Where the README warns, audio is "a bit garbled/distorted."

What ktnes supports

NES (Nintendo Entertainment System)
Android (build from source via Android Studio or Gradle)
Web (JavaScript target; run locally with Gradle web:run)
JVM / Kotlin Multiplatform native targets (via Gradle and Kotlin/Native)

Download and availability

OFFICIAL DOWNLOADS

Get ktnes

Official source and any release artifacts are served from the project's GitHub repository. Check the repository's Releases page for prebuilt packages; otherwise build from source with Gradle.

Get ktnes ↗

DOCUMENTATION

Official documentation

Read the official configuration, compatibility, and troubleshooting material before changing advanced options.

Read official documentation ↗

Broken or missing download? Emulator projects move and official links sometimes change. Please contact Retro Replay so the source can be verified and updated.

ktnes setup guide

Setup note: This guide shows how to fetch and build ktnes from the official source and run the two primary reference targets (Android and web). It assumes you are comfortable using Git and a Gradle-based Kotlin toolchain. The repository uses Gradle wrapper scripts so you can build without installing a specific Gradle version system-wide.

1) Obtain the source: Clone the official repository from GitHub: git clone https://github.com/felipecsl/ktnes. Inspect README.md in the project root for up-to-date notes before building.
2) Prepare your environment: Install a JDK (OpenJDK 11 or newer is commonly required for Kotlin projects), and ensure the Gradle wrapper (./gradlew) is executable. For Android builds, install Android Studio and the Android SDK/NDK components required by your Android Studio configuration. For the web target you only need a JDK and node (if you plan to run production builds), but the repository’s web:run task uses the Gradle dev server and opens on localhost.
3) Build and run the Android target: Open the android module in Android Studio and run or debug as usual. Alternatively from the project root you can run: ./gradlew android:installDebug which builds and installs the debug APK to a connected Android device or emulator. Use Android Studio for easier device and permission management.
4) Build and run the web (JavaScript) demo locally: From the project root run: ./gradlew web:run. The README indicates this will start a local server; then open http://localhost:8080 in a browser to use the JS build. If the Gradle run task fails, inspect web module build files and browser console for errors and ensure your local ports and Node/JDK versions meet the requirements in build files.
5) Running other native/JVM targets: The project uses Kotlin Multiplatform. Use the Gradle wrapper to assemble the relevant artifact for your target. Typical commands are ./gradlew assemble or ./gradlew build; examine module-specific build.gradle files for target-specific options. For Kotlin/Native targets you may need platform-specific toolchains (Xcode on macOS for Apple targets, and appropriate Kotlin/Native prerequisites for Linux/Windows).
6) Mapper compatibility and testing: ktnes documents which mappers are implemented (Mapper 0, 1, 4/MMC3). If a game uses an unimplemented mapper it will not run correctly; test games that are known to use implemented mappers and consult the repository issues for reports on game compatibility.
7) Troubleshooting and development notes: If audio is garbled or you encounter crashes, check open issues in the GitHub repository and search the commit history for fixes. Because this is a development-focused implementation, expect that some features are experimental and follow repository issue/pr threads for workarounds and fixes.

Software reminder: ktnes does not include commercial game ROMs, console firmware or BIOS files. You are responsible for obtaining any ROMs and other files legally. Follow copyright and platform laws in your jurisdiction.