Steam will halt support for macOS 10.13 and 10.14 (better known as High Sierra and Mojave) on February 15, 2024.

The move means existing Steam Client installations on those operating systems will no longer receive updates of any kind, including security updates. As detailed in a blog post, Valve will also be unable to guarantee Steam will continue working as intended on those unsupported operating systems.

Notably, Mojave is the last version of macOS capable of running 32-bit games, with Apple dropping that particular functionality with the launch of macOS 10.15 in 2019. That means some titles will no longer function on macOS once Valve has cut support for macOS 10.14.  

“Since many developers have not updated their games to support 64-bit executables, some games will effectively stop functioning on macOS. The Steam store will stop considering games that offer only 32-bit macOS binaries to be Mac compatible at the end of 2023. 98%+ of Steam customers on Mac are already running macOS 10.15 or newer. This means 32-bit only games and applications no longer run on your current operating system,” explains Steam Support .

“In order to ensure continued operation of Steam and new 64-bit games purchased through Steam, users on these older versions should update to a more recent version of macOS. We expect the Steam client and games on these older operating systems to continue running for some time.”

Valve reiterated that it will be unable to guarantee the “continued functionality” of 32-bit macOS titles after February next year, but said it needs to drop High Sierra and Mojave due to a lack of certain macOS features and security updates that are only present in macOS 10.15 and above.

The company is encouraging all High Sierra and Mojave users to update “sooner rather than later” and noted that Apple ended security updates and technical support for both operating systems in December 2020 and October 2021, respectively.

“Computers running these operating systems, when connected to the internet, are susceptible to new malware and other exploits which will not be patched,” it continued. “That malware can cause your PC, Steam and games to perform poorly or crash. That malware can also be used to steal the credentials for your Steam account or other services.”