To get started, you’ll need a legitimate copy of Half-Life 2: Deathmatch on your Steam account and a reasonably powerful Android device.

Then Admin_Spectre typed:

Modern mid-range and flagship processors (Snapdragon 8 Gen 1 and above) can easily run the game at 60+ FPS. Because the Source engine is so well-optimized, even older devices can handle the mayhem, though you may need to lower the resolution.