Steam error: “You are missing the following 32-bit libraries, and steam may not run: libXtst.so.6 libgtk-x11-2.0.so.0”
Solution 1:
You can get the 32 bit version of those two .so's by installing these packages:
sudo apt install libgtk2.0-0:i386
sudo apt install libxtst6:i386
The ":i386" suffix specifies the 32 bit version of the package. Note that this step may be a prerequisite (it doesn't seem to be for me, but people often report that it is).
sudo dpkg --add-architecture i386