Steam

This guide is for installing on a 64-bit system.

Make sure the user that will use steam is part of video and audio groups
- groups {user} to check the groups
- usermod --append --groups video,audio {user} to add the user to the groups
Make sure that non-free repositories are enabled in /etc/apt/sources.list
Enable multi-arch support (steam is actually packaged as a 32-bit application). Debian wiki page on multi-arch
- dpkg --add-architecture i386
- apt update
apt install steam
Install 32-bit libraries for your graphic card: see the debian wiki page

Steam will auto-update when you start it, so make sure you have a good enough internet connection when first starting it.

Downloaded games will be by default installed in ~/.steam/steam. This folder can get very big!