Cities: Skylines Remastered is released for consoles. Almost all of Paradox Interactive's games have a Mac port so I checked if they have updated the game for AS but it seems they are a small developer with no dedicated Mac team so
they won't support AS. Despite the fact that their games work in Rosetta they're officially unsupported on AS.
"Support for newer hardware is unfortunately not feasible. This is not exclusive to Mac users, but as Apple Silicon is used in more and more Macs, it does affect our Mac players more. We do not have a dedicated Mac development team, we are not that large a studio that we have devs dedicated to one OS alone. Providing support for Apple Silicon would require a significant amount of work, which I'm afraid just isn't feasible for us to do."
"I understand this is not the response you were hoping for and for that I am sorry. We also wish this was something we could easily provide for our Mac players, but unfortunately, that is not the case. I hope you are still able to enjoy the game, both playing and modding it. The built-in C# compiler had to be dropped from Mac due to notarization issues. I'm afraid that isn't something we are able to support again. ModTools uses that compiler, which is why scripts do not work on Mac. It would be possible for ModTools to include its own compiler, though of course, that would require the modder to add that, which they may not want to or be able to do."
"I just want to clarify what "not supported" means to avoid any confusion. It means we can't guarantee the game runs as it should on that hardware. We have players who have had great experiences playing on Apple Silicon and we have had players who have run into issues. As the hardware is unsupported, it means any issues specific to that hardware may not be fixed."