This very simple script (it's less than a hundred lines long) can set your laptop's backlight as long as it's using an Intel GPU. It doesn't do much and it isn't smart, but in return it requires no dependencies.
Run make.
Set using commandline arguments:
# ./blight [desired percentage between 1 and 100]
To do the same interactively:
# ./blight.
Must be run with root privileges.