When I try to open Steam through GNOME, it just loads and stops. When I try to open it through terminal, I get the message
QuoteInstalling breakpad exception handler for appid(steam)/version(1490228413)
libGL error: unable to load driver: nouveau_dri.so
libGL error: driver pointer missing
libGL error: failed to load driver: nouveau
libGL error: unable to load driver: swrast_dri.so
libGL error: failed to load driver: swrast
Check here, for example:
https://askubuntu.com/questions/635851/error-in-installing-steam-on-ubuntu-15-04