I started HalfLife2 in window mode. And the app could connect and display normally with router connection, but the head track could not work when I move my Android smartphone. I am not sure if the hardware could support or something wrong. And can I find some log or output anywhere? Thanks.
There are some limitations on tracking depending on the hardware. Latest version of the app should show a message if your device has such limitations (I do plan to improve the system to minimise this). Please try with the current version of Trinus Gyre and see if there is mouse movement (sensor type should be set to mouse for fps games like HL2) when connected.