FYI the launcher and game work fine on my iMac with 11.15.2
I think you have at least 2 separate problems. For the launcher Please delete the
~/Library/Application Support/Paradox Interactive/ folder. To see it go to the Finder, hit command-shift-G (ie Go To) and paste in
~/Library/Application Support/ . Then run the game from the PLAY Button in Steam, to reinstall the launcher.
If that does not get the launcher running, we will need these files from that same folder:
Attach ALL .log files Found here ~/Library/Application Support/Paradox Interactive/launcher-v2/
Those game errors all relate to mods. Check your installed mods against this list:
Broken Cities Skylines | List of Broken mods These mods are all broken, dead, or not compatible with the current version of the game. Please read the 'Issue' column before making assumptions! If there is a replacement, it's listed in the green row under Replacement. Links provided for quick uns...
docs.google.com
If you still get those errors after removing or replacing all bad mods, Please attach this log file here:
~/Library/Logs/Unity/Player.log
To find that file, in Finder do cmd-shift-G to bring up the GOTO box. In there paste ~/Library/ . You will see a /Logs/ folder, and inside that /Unity/ folder. Please attach that file player.log here by dropping it on this support ticket, or use the "Attach file" link here.
Also in Steam please click on Steam-Help-System Info, and paste everything there into a text file and attach that here.