I have macOS Mojave beta installed and so far Sims 3 is still loading and playable.
I did get the following dialogue box stating that the game will stop working at some point with a future version of macOS, not dissimilar to the one currently popping up in High Sierra and linking to the same Apple support page:
I also tried Sims 4 and was surprised to get a similar dialogue box. Origin and Sims 4 are already 64-bit so this message shouldn’t be popping up:
I really have no idea what software this dialogue box is referring to. If anyone has any idea please share, it would be great to know 🙂
I’ll keep testing after each build is released and report any changes here.