@t0nai That does sound strange. For now, leave Origin out of the picture. (You don't have to uninstall it, just don't open it.) Under System Preferences, check your settings in Security & Privacy to make sure that your firewall is off (third tab) and you're allowing apps from identified developers as well as the App Store (first tab). Mojave's security features are more strict than those of its predecessors, but TS3 is certainly still playable.
If this doesn't help, try launching the game while your computer is completely offline. Since you haven't been able to open it since your reinstall, you won't get very far. I'm just wondering whether this will change anything. If you get an error message, please post a screenshot. You can grab one by pressing cmd-shift-4 and dragging your cursor over the section you want to capture.
Oh, also disable iCloud temporarily. I have no idea if this has anything to do with it, but the game closes exactly when it would be generating a user folder, the one that lands in Documents. Maybe iCloud changed its settings when you updated to Mojave; it's been known to do so. If it's trying and failing to sync or upload Documents to cloud storage, that might explain the problem.
Let me know, and I'll try to figure out what's going on. And I'll definitely ask Bluebellflora for her thoughts too, when she has time.
