How to Exclude Steam Games from Time Machine

by Rian

One of the obvious challenges of using Time Machine is that not all apps and databases are optimized to use automatic backup. Or to be more blunt on the subject, with modern video games ranging roughly up to several hundred gigabytes with day one patches that are equally large, Steam has been enabling developers to distribute unfinished and unpolished games without repercussion.

But now is not the time to delve into Steam policies; that’s what an op-ed is for. The real problem behind the Steam’s odd choice of policies and behaviors is that it does not exclude its games (i.e. games that are installed locally) from Time Machine. Had you installed a game that is roughly 100 GB, with day one patch of equivalent size, there’s a good chance it will take up 200 GB on the Time Machine destination drive. That is not the desired behavior, as Time Machine should only keep track of changes.

Thanks in part to frequent updates, technically there is no benefit in creating a backup of your Steam Library; you would need to install some large updates if you come back in the future. In other words, except for few minor cases, it would be better to simply exclude Steam games from Time Machine. Run the following command on Terminal, with [username] replaced with your own:

tmutil addexclusion "/Users/[username]/Library/Application Support/Steam/SteamApps/"

Backups growing exponentially in certain cases is a known Time Machine behavior, which happens most often with virtual machines, as Time Machine cannot parse them; so it chooses to backup the entire system even with the slightest changes. Normally, when an application may not work proper with Time Machine, say, Parallels or VMware, they automatically add themselves to the excluded list. I’m surprised Steam doesn’t do that.