Ok, it looks like PatchLoader wasn't running. Did you run game from script(commandline param or launcher-settings.json "exePath" value change)? Also there is a problem if you start the game before steam client -> You need to run Steam first then the game (shortcut/steam client or whatever you like).

I always run Steam first because updates to mods, assets. And I have this in my startup options for CS - /home/USER/.steam/steam/steamapps/common/Cities_Skylines/Cities_Loader.sh %command% - I have found that letting the launcher open then running the game does the same thing.

Is there something else I need to put as a launch option?

**EDIT - changed to correct Launch Option path**

Instead of Cities.x64 put Cities_Loader.sh(it will launch Cities.x64 anyways).

Originally posted by Krzychu1245:

Instead of Cities.x64 put Cities_Loader.sh(it will launch Cities.x64 anyways).

This worked. How do I mark this as the correct answer?

I'll pin it. You can change title to something more descriptive to help other people find it if they have similar issue.
Maybe something like this: [SOLVED] FPS Booster does not work on Linux

Done.

And thank you for such an essential mod!!

Well hello, for some reason I don't have Cities_Loader.sh nor do I have Cities.x64 but "Cities.exe"
What should I do to fix it please ?

Note that I'm using a trick to not have the launcher, should I remove the fix to not have the stupid launcher?

Are you on Linux? If so, why don't you use native version?

Because there is no more .x64, now the game is released as a mono executable that is directly runnable via mono, even on linux. Patch Loader now work without intervention in the json, but FPS Booster is still unhappy.

@Kane - not sure what you mean. I just looked and there is still the .x64 file. Also, I have edited one of my responses above to reflect the correct path in Launch Options. The correct path is - /home/USER/.steam/steam/steamapps/common/Cities_Skylines/Cities_Loader.sh %command% - where I believe you will find the .x64 file.

Originally posted by Kane:

Because there is no more .x64, now the game is released as a mono executable that is directly runnable via mono, even on linux. Patch Loader now work without intervention in the json, but FPS Booster is still unhappy.

If you run game with proton you will get exe file but mod won't work. On the FPS Booster options page it should show it's active and running. If it's not active then popup about critical error is still valid

Hooo, I'm sorry, I don't know why, proton was enabled… I disabled it, now everything work as expected !!!! Sorry

I can't get this to work on Steam Deck. I set compatibility mode to "Steam Linux Runtime".

The command lines posted here didn't work, but eventually I used "/run/media/mmcblk0p1/steamapps/common/Cities_Skylines/Cities.x64 %command%" (no qoutes) which worked for me at first, but then I enabled all my mods and the game crashed, then it wouldn't load it back up. I had to restart with default compatibility + no command line to disable all my mods.

Now when I start with the same compatiblity mode + command line and all mods disabled, it will load up to the Paradox Logo, then crash without generating any logs.

I don't have a steam deck. Game cannot run wth Proton compatiblity mode. Only native is supported, if doesn't work then I have no idea what changed or how to fix it.

Alright. With more searching, I discovered that you have to start with medium textures or it will run out of RAM, and even then it's really slow, and possibly wont save anything,so Linux compatibility for Steam Deck is a bad idea. Hopefully the sequel will have better performance changes.