Main.22.com.nvidia.valvesoftware.halflife2.obb -

in the middle of your filename stands for the version check. Ensure that the specific Half-Life 2 APK installer you are using matches version 22 (or is designed to read version 22 assets), otherwise the game will fail to launch and will ask to download resources. Are you attempting to run this on a native NVIDIA Shield device or are you using a Source Engine wrapper on a standard Android phone?

If you are not using an NVIDIA SHIELD device, note that the official Half‑Life 2 Android port was never released for general Android phones/tablets. Running it on other devices requires unofficial modifications and is not covered here. main.22.com.nvidia.valvesoftware.halflife2.obb

It is a phantom file generated by either: in the middle of your filename stands for the version check