Steam dropped support for PCs running Windows 7, Windows 8, and Windows 8.1 earlier this week. Now, the games store and platform is preparing to cut off older macOS releases as well.
Valve announced on its support site that Steam will end support for macOS 10.13 High Sierra and macOS 10.14 Mojave on February 15th, 2024. The Steam application and supported games won’t stop working immediately, but Valve won’t offer any technical support for people on those operating systems, and continued functionality is not guaranteed.
The stated reason is the same as the recent removal of Windows 7 and Windows 8 support: Steam uses an embedded version of Google Chrome (specifically, the open-source Chromium) that is no longer being patched on those older macOS versions. Valve also says 98% of Steam users on macOS are already running macOS 10.15 or newer.
Unfortunately, this change also means most older macOS Steam games will be completely unavailable from Steam. Valve said, “Apple chose to drop support for 32-bit applications in macOS 10.15 (released 2019), and 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.”
Many of Valve’s own games were never updated for 64-bit macOS, including Half-Life 2 and its sequels, Team Fortress 2, Left 4 Dead 2, Portal, and Portal 2. Counter-Strike: Global Offensive was also in that category, but when Valve revamped it as Counter-Strike 2, it dropped support for macOS entirely and the original game was removed.
The older Steam releases of the Grand Theft Auto series are also unavailable on 64-bit macOS (the recent remasters are not on Mac either), as well as the Steam versions of Civilization VI, BioShock Infinite, SimCity 4, and others. In some cases, like with SimCity 4, updated versions are available only through the Mac App Store.
The Windows versions of many older games can be played on modern Macs, using tools like CrossOver and Parallels Desktop, but those are paid products and don’t work with every game. Intel-based Macs can still play the Windows versions by installing Windows through Boot Camp.
Source: Steam Support