Not only games, but all your non-Apple Applications are subject to this change. As with all macOS updates that break prior games in your library, Catalina is no different (except that it will break a lot more than usual). Upgrading to Catalina will cause all 32bit-only Applications to cease functioning! You will not even be able to launch them. Pardon my bluntness, but what Csound means is that the Boot Camp forum is for issues with installing Windows on your Mac or related issues. Your issue is NOT with Windows, nor with Mac, it is with the game in Steam. So you need to ask over at Steam. Your issue is no different than a person with a Dell PC running Windows saying Elder Scroll crashes.

Apple has ended 32-bit support with the release of OS Catalina, meaning many older games purchased may not run on the free OS update.

Moreover, Steam users will also want to hold off on the update, as the Steam client itself is a 32-bit application.

MacGamerHQ has compiled a list of affected games on MacOS, with many games like the LEGO games no longer working in the new OS.

As of this writing even Valve’s first-party games like Team Fortress 2 and Portal, some of the first high profile games to come to Mac, have also been affected by the update.

While the update may seem sudden, users of High Sierra and Mojave will probably have encountered warnings that Apple would make the sheer jump to 64-bit only.

How To Play Windows Only Steam Games On Mac Catalina 10.15

No statement has been issued by Valve or Apple regarding the issue as of this writing.