Get COD 4 running on a Mac whilst enabling the Mac to upgrade to Catalina and beyond and not having to reboot in an older OS in order to run it.
Firstly forget using Parallels to emulate an older Mac. Will not support 3D. Probably Apple breathing down their neck not wanting people to keep supporting older Mac OS except in a limited fashion.
Subsequently instead of using a Mac virtual machine I instead used my Windows 10 VM I already had available and fully updated it along with all the Parallels drivers. I have a second COD 4 licence via Steam so I installed it and voila! 3D accelerated Cod 4 on my Mac. It runs really well from first testing. Haven't seen how far I can ramp up the resolution and textures yet but when I have time I will add to the story. Best news is that the new Parallels (v15) which is coming out when Catalina is launched is going to support Apple's Metal 2 graphics engine and therefore will provide enhanced 3D support to Winblows virtual machines. Might give me more oomph. My Mac is a 27" Retina iMac with quite a reasonable 3D card in it so people's mileage may vary on older generation Macs that can run Catalina but only use integrated graphics and not discrete. However given that COD 4 was built some time ago its demands on 3D hardware aint nothing like modern games. For the record I had to downgrade COD 4 from the steam version 1.8 to v1.7 to enable it to support the Ninja Servers which use a previous version of the multiplayer protocol.
The things we do for a bit of fun! 😂