Please try a clean reinstall:
- Remove the game from Steam (delete local content)
- Manually delete all these files and folders, if still there:
...\Steam\steamapps\common\Cities_Skylines\
...\Steam\userdata\<SteamID>\255710\
...\Users\<UserName>\Documents\Colossal Order\Cities_Skylines
...\AppData\Local\Colossal Order\Cities_Skylines
(first move the /saves/ folder elsewhere to keep your save games)
- In the Steam Workshop, un-subscribe from ALL mods and assets
- Install the game again, but BEFORE running for the first time, in Steam right-click on this game and choose Properties. Click on Set launch Options, and paste this in there: -force-d3d9
- Now run the game up and start a new city.
- If all goes OK, move the save games back and try again.
- If still OK, you can start subscribing to mods and assets again. But test the game after every few, to make sure a bad one has not come down again.
IF that doesn't help:
DXDIAG is a program you run from a command prompt or the Windows start menu 'run' dialog box (or 'search programs' in Windows 7). After running it will open a window and start collecting info with a progress bar in the lower-left corner. When it completes click the 'save all information' button and save it to a file then attach that file here.
Please attach this log file:
...\Steam\steamapps\common\Cities_Skylines\Cities_Data\output_log.txt
