Installation from Ubuntu Repository
The easiest way to install STEAM on Ubuntu 16.04 and up is by using apt-get command to fetch steam installed directly from Ubuntu’s multiverse repository:
sudo add-apt-repository multiverse sudo apt-get update && sudo apt-get install steam
If you get error fellow this method and try again
Getting a ‘package not found’ error? If so, you need to enable the multiverse repository first.
This can be done in one of two ways:
1 Open ‘Software & Updates’ from the Unity Dash
2 Go to the ‘Ubuntu Software’ tab
3 Check the box next to ‘Ubuntu Software Restricted by Copyright (Multiverse)‘
4 Click ‘Close’
