[2020] tech issue

'mymap 2' is failing to load and the file looks like it might be corrupted, so I don't have any options for what we can do with that I'm afraid. Do you have an older version of the same or an autosave to try instead?

The game suddenly having problems while you are playing sounds like overheating to me. You can use a free program like speedfan to check the temperatures for your CPU and GPU while the game is running.

Hmm strange! Do both mymap2 and 3 load fine? It sounds like the original mymap is corrupted. If the game no longer "sees" it then something has usually gone wrong with the file.

Clearing traffic helping sounds like it's your CPU being unable to keep up. Definitely check the temperatures to make sure it doesn't go too high. Under 80C I wouldn't be worried about, but above that would indicate it might have a cooling problem, leading to the performance issues you see. But it might simply also be that there are so many citizens and vehicles on your map, that it can't keep up. It wouldn't explain why it suddenly appeared though.

What's the CPU temperature when that happens?

Not the temperature then! 40C is very good. Try running the game with the launch options -noWorkshop and -disableMods and test on a new city to see if it happens there too. This will tell us if it's mod related or not.

How To Set Launch Options

• Right-click on the game title under the Library in Steam and select Properties.
  
• Under the General tab click the Set launch options... button.
  
• Enter the launch options you wish to apply (be sure to separate each code with a space) and click OK. Should look like this:
  -noWorkshop -disableMods
• Close the game's Properties window and launch the game.

It's a mod then. If you can post your output_log.txt (called player.log on Mac and Linux), then I'd be happy to take a look at your mods. :)

Here's where to find the log depending on your operating system. To easily find the local files for the game, right click your game in the Steam library, select Properties, go to the Local Files tab and select Browse local files.

Windows
\SteamApps\common\Cities_Skylines\Cities_Data\output_log.txt

Mac OS X
Users//Library/Logs/Unity/Player.log

Linux
~/.config/unity3d/Colossal Order/Cities: Skylines/Player.log

As we can't attach files here on Steam, you will need to upload the file somewhere else. Here's a few sites you can upload it to, which do not require you to sign up first:

https://uploadfiles.io/ - free, no sign-up, can handle large log files
https://paste.ee/ - fast, no sign-up required (some log files will be too large for it though)
https://zerobin.net/ - bit clunky, but can handle huge files, no sign-up required