Re: Sims Medieval not working on a new MacBook

@sandutchen  I take it your Mac runs Catalina?  There's no workaround to make the game run in Catalina, because the OS is 64-bit only, and Sims Medieval is a 32-bit app.  However, what you could do is install Mojave or earlier on an external hard drive or USB stick, then boot into that when you wanted to play.  Aside from the external, you'd need at least temporary access to a Mac running Mojave or earlier.

https://bluebellflora.com/running-32-bit-apps-after-macos-mojave/

You could also reinstall the original OS that came with your Mac, then update to Mojave (but not Catalina).  Although the process is supported by Apple, it's not without risk, but when it works correctly, user data is preserved.

https://support.apple.com/en-gb/guide/mac-help/mchlp1599/mac

Or you could install Windows on your Mac, via either Bootcamp or Parallels.  You'd need enough free storage to devote to Windows and the game, plus a Windows 10 product key.  Let me know if you want more information about this process.