@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.
@puzzlezaddict Unfortunately, none of the above helped. I changed my security settings, logged off my iCloud, deactivated my Wifi connection and left origin unopened. Still, the Sims icon appears in my dock for a moment, then the application closes again.
@puzzlezaddict I tried running the game on a different user on my Mac. The „unknown error“ message popped up. Then I tried bypassing the launcher by changing the info.plist file. A new error showed.
„The Sims 3 - Unable to start game. Service initialization failed (0x0175dcbb)“
@t0nai That's actually good news; the unknown error we understand and can usually fix (not always, but usually). Is there anything different about that new user account, like is one of them admin and the other not, or are the settings different? This is for my curiosity and future troubleshooting; feel free to leave the question alone.
In your case, with only the base game installed, you'll need to edit two .sgr files in TS3's program files to force the game to recognize your graphics card. Some iMacs come with dedicated graphics cards, and others don't. The specs you listed refer to an integrated card, but if you have both, the dedicated card might not have been listed in the initial specs. So please go to About This Mac again, then click System Report, then Graphics/Displays, and let me know which card(s) you see listed. Once I know which card you have, I can send you instructions for the edits, or a link to instructions if Bluebellflora has already prepared the text for your card.
Also, undo the edit you made to bypass the launcher. That can come later, if you want.
I only have the integrated Intel Iris pro 1536 MB card.
This is what my report says (unfortunately in German, but I guess the most important stuff is understandable):
Chipsatz-Modell: Intel Iris Pro
Typ: GPU
Bus: Integriert
VRAM (dynamisch, maximal): 1536 MB
Hersteller: Intel
Geräte-ID: 0x0d22
Versions-ID: 0x0008
Metal: Unterstützt, Funktionsset macOS GPUFamily1 v4
Displays:
iMac:
Displaytyp: LCD
Auflösung: 1920 x 1080 (1080p FHD - Full High Definition)
UI sieht aus wie: 1920 x 1080
Framepuffertiefe: 24-Bit Farbe (ARGB8888)
Hauptdisplay: Ja
Synchronisierung: Aus
Eingeschaltet: Ja
Rotation: Unterstützt
Helligkeit automatisch anpassen: Nein
Verbindungstyp: DisplayPort
Last time I checked Bluebellflora only had instructions for the late 2013 21“ iMac (iMac 14,1) with the Intel Iris Pro 5200
