Go to Settings > Security (or Privacy ) and allow installations from unknown sources.
Features a massive library of weapons, often including futuristic or non-standard CS guns.
You typically install a single APK and move an "OBB" or "Data" folder into your Android's /Android/data/ or /Android/obb/ directory. ⚡ Key Features of V7 New Characters: Play as zombies, robots, or special forces.
This is the most stable method. It uses an engine that allows the original Half-Life (and its mods) to run on Android.
True Android "downloads" for this game are usually structured as a combination of an APK (to run the engine) and a "data" folder (containing the CS Extreme V7 assets).