tomred@tomredPC:~/Desktop$ sudo dpkg -i steam.deb
[sudo] password for tomred:
Selecting previously unselected package steam-launcher.
(Reading database ... 251213 files and directories currently installed.)
Preparing to unpack steam.deb ...
Unpacking steam-launcher (1.0.0.54) ...
Setting up steam-launcher (1.0.0.54) ...
Processing triggers for desktop-file-utils (0.22-1ubuntu5.2) ...
Processing triggers for bamfdaemon (0.5.3~bzr0+16.04.20180209-0ubuntu1) ...
Rebuilding /usr/share/applications/bamf-2.index...
Processing triggers for gnome-menus (3.13.3-6ubuntu3.1) ...
Processing triggers for mime-support (3.59ubuntu1) ...
Processing triggers for hicolor-icon-theme (0.15-0ubuntu1) ...
Processing triggers for man-db (2.7.5-1) ...
tomred@tomredPC:~/Desktop$ steam
Repairing installation, linking /home/tomred/.steam/steam to /home/tomred/.local/share/Steam
Running Steam on ubuntu 16.04 64-bit
STEAM_RUNTIME is enabled automatically
Installing breakpad exception handler for appid(steam)/version(0)
libGL error: unable to load driver: radeonsi_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: radeonsi
libGL error: unable to load driver: radeonsi_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: radeonsi
libGL error: unable to load driver: swrast_dri.so
libGL error: failed to load driver: swrast