You can take Counter-Strike on-the-go now, thanks to this unofficial port.
The Android hack for Counter-Strike v1.6 was created by modder Alibek Omarov, who has brought older PC games to the OS in the past.
It also supports controller peripherals through a USB adapter, if you aren't keen on touchscreen shooting.
Omarov was also one of those responsible for getting Half-Life to run on Android. In order for either game to run on Android, users will need to the title on Steam, and download Xash3D. This will copy the games across files.