Nvidia

In short: ALT packages nvidia drivers (as well as bbswitch/bumblebee/primus), so just

apt-get update && apt-get dist-upgrade
apt-get install update-kernel nvidia_glx_common
update-kernel; nvidia-install-driver

and reboot with the new initrd; you can also use acc and select Graphical interface/Display module to configure the GPU driver explicitly (this will also take care of the initrd image).