Unable to locate package steamcmd

Ok, I found the answer myself.

First I needed to add multiverse to my /etc/apt/sources.list:

deb http://archive.ubuntu.com/ubuntu xenial main universe multiverse
deb http://archive.ubuntu.com/ubuntu xenial-updates main universe multiverse
deb http://archive.ubuntu.com/ubuntu xenial-security main universe multiverse

afterwards I added the i386 architecture:

sudo dpkg --add-architecture i386

now after an apt-get update I am able to install it.

sudo apt-get install steamcmd

Run these commands:

sudo add-apt-repository multiverse 
sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install lib32gcc1 steamcmd

Hope this will help. Or you can check source here:

• How to Install Steamcmd on Ubuntu Server 16.04 LTS | Xenial Xerus