This is the key part of the script
xset s noblank &
xset s off &
xset m 1/4 1 &
steam -tenfoot &
The first line starts Openbox as a window manager.
The xset lines do the following:
xset s noblank – Stop the screen from blanking due to inactivity
xset s off – Disable screensaver and monitor power management, preventing it from going into sleep mode.
xset m 1/4 1 – Mouse Acceleration (1/4th) and precision (1 pixel), feel free to tweak these to your liking or commenting out this line if you like the defaults.
The last line is the command which starts Steam in Big Picture mode, courtesy of the -tenfoot flag.
Personally I recommend setting Openbox to spawn only borderless windows. Since you’re going to be gaming in this session, most likely window borders will only take real estate and, this way, you can set all games to your monitor’s/TV resolution in Windowed mode (allowing for Alt+F4 killing if they lock up).
In order for Openbox to spawn all windows without decoration, navigate to:
Scroll all the way down to the applications section and add these lines before the end of the section (/applications):
All windows will now be borderless on Openbox.