This is not a commercial release. The game runs using community-created engine ports (e.g., Xash3D for Android) together with original CS:CZ game files copied from the PC version. You generally need to own the original PC game legally to extract the required .pak / .bsp / sound files.
Buy/Download if: You are a CS veteran who misses the old days and doesn't mind spending 20 minutes setting up file directories. Use a controller.
Avoid if: You want a polished mobile FPS like Standoff 2 or Critical Ops. This is a clunky, fan-made passion project.
The closest modern analog to Condition Zero. Features:
CS:CZ is surprisingly demanding because it was not optimized for ARM architecture. Running it via an emulation layer (Xash3D) can drain a 4000mAh battery in 2 hours and cause significant thermal throttling.
Verdict: It is playable for casual bot matches on easy difficulty. It is not competitive. The precision required for headshots on de_aztec is nearly impossible without a physical keyboard and mouse (which Android supports via USB OTG – a recommended setup).
The closest you can get to a native experience is not CS:CZ directly, but CS 1.6 running on the Xash3D Android engine. Xash3D is an open-source re-implementation of the GoldSrc engine (the engine CS:CZ runs on).
While Xash3D is primarily built for Half-Life and CS 1.6, dedicated modders have successfully ported Condition Zero assets to work on this engine.
How to play CS:CZ on Android via Xash3D:
Result: You get 60 FPS, touchscreen controls (customizable), and full single-player bot matches. However, the "Deleted Scenes" campaign is notoriously difficult to run on Xash3D and often crashes.
If you are tempted to download a pre-assembled APK+OBB from MediaFire, Mega, or a random forum, consider these dangers: