Android Goldsrc / Source engine ports by nillerusr
Ports of NVIDIA SHIELD releases, works on unrooted, non-NVIDIA devices
Here is a port of the NVIDIA SHIELD versions of Half Life 2 and other source games to non-tegra android devices. Contains the original game files directly from NVIDIA's servers before they were taken down which are needed to play the game.
This is the work of Lithuanian developer nillerusr.
I can't guarantee that this will work on every device, but it worked on mine.
instructions from plebbit