These instructions are written for a 64-bit Ubuntu installation. Modifying them for other linux distributions should be little to no work. If you're running Windows you're on your own.

• Download and extract the Android SDK tools: https://developer.android.com/studio/index.html#command-tools
• Download and extract the Android NDK (r19c or later): https://developer.android.com/ndk/downloads
• Install JDK 8. Required by Android SDK manager.
• Install bison and flex. Used by the native nethack build.
• Check out NetHack-Android: git clone https://github.com/gurrhack/NetHack-Android.git
• Create an env variable called ANDROID_SDK_ROOT and point it to the android-sdk installation directory. Used by Gradle.

1. cd /path/to/android-sdk/tools/bin
2. Update the sdk manager: ./sdkmanager --update. If you get "NoClassDefFoundError" it's because you're not running JDK 8. Make sure the env variable JAVA_HOME points to JDK 8.
3. Install the platform tools: ./sdkmanager --install "platforms;android-30"

1. cd /path/to/NetHack-Android/sys/android
2. Open Makefile.src and change NDK to the appropriate path.
3. sh ./setup.sh
4. cd ../..
5. make install

1. cd /path/to/NetHack-Android/sys/android
2. ./gradlew build
3. cd ./app/build/outputs/apk/debug
4. Copy the APK file from this directory to your device.
5. On your device: locate the APK file, install it and run!

Happy hacking!