Install the Xash3D FWGS app from the Google Play Store.
While there is no native version of Half-Life 1 on the App Store or Google Play Store, the game is fully playable on modern mobile devices through powerful fan-made engines and community projects. half life 1 mobile
The most popular and stable method is using the Xash3D FWGS engine . This is a custom engine that allows you to run original GoldSrc games (the engine HL1 was built on) natively on your phone. How to Install on Android Install the Xash3D FWGS app from the Google Play Store
Playing on iOS is more difficult due to Apple's "walled garden" and requires sideloading: half life 1 mobile
Find your Steam installation (usually Steam/steamapps/common/Half-Life ) and copy the entire valve folder into the xash folder on your phone.