- Install the .deb from steam:
sudo dpkg -i steam_latest.deb.
- Fix the proken dependencies (because Steam does not just use the default terminal emulator…):
sudo apt-get -f install(it will pull in xterm).
To run Steam in Freya on a 64-bit machine, you need a 32-bit environment. However, as ElementaryOS is based on Ubuntu LTS, you can’t install the “normal” libGL/Mesa libraries as Steam tries to do. In stead, you need the LTS versions. So before running Steam, do
sudo aptitude install libgl1-mesa-dri-lts-trusty:i386 libgl1-mesa-glx-lts-trusty:i386 libc6:i386.
Now you can start Steam!