"immediately upon exiting the loading screen."
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So you mean after the logo screen and stuff during startup but before the main menu displays, Or do you mean it crashes when you go to exit the main menu to exit the game, or the loading screen while loading a map as it transitions to the game screen?.
First I would ask if anything changed about your system since the last time you played successfully? Installed any other games, system level software (antivirus\antimalware\etc), updated drivers, hardware, or changed video card settings etc, I don't expect you to really know but I gotta ask as it can points to possible causes in the behavior change.
Also the log file in your Steam\steamapps\common\Cities_Skylines\Cities_Data\output_log.txt might provide some idea of how far it got before it crashed.
If you can't get into the game, can I ask how you're uninstalling mods? You just renaming the workshop folder to disable them all or something?
Does it load with -noWorkshop -disableMods in your launch parameters? What about with --force-d3d9 (this might avoid some new video card driver issue that maybe popped up, or if you were already using that switch try without it) or with forcing a specific resolution?
Could try *backing up first* (else lose milestones and game settings stuff) and then killing %User%\AppData\Local\Colossal Order\Cities_Skylines\ gameSettings.cgs and userGameState.cgs maybe they got corrupted.
