Download extract and run the attached .reg file and confirm the insertion of the Keys, then reboot the system.
Alert to make a backup of the old keys if you want to restore the previous state.
This change is compatible with all windows 8 but I have tested only on the surface.
Adaptive brightness varies proportionally to the user manual brightness, I suggest to manually adjust the brightness bar to about 20%, if you place the bar at 0 the brightness will be minimal with no automatic adaptation.
New version v2
New improved version.
Try it and tell me if it's okay.
In the zip you will find the normal version and one with more brightness in the dark
I suggest to manually adjust the brightness bar to about 25%