Game shows black screen only on startup, Mac

I've got the same problem as a few others on this forum. Before I tried out the Ultra settings for my Macbook Pro (2011), everything was running great for that Mystery Lake map. Coastal Highway never worked anyway because of the aweful lag, but now I can only see a black screen on startup.

This means I can't go to Options and change the graphics back to High again, because I can't see anything. There's still audio, though.

I tried reinstalling a few times, no luck there. On this forum I read that someone did a complete uninstall of The Lone Dark by deleting hidden items Steam did not remove during the uninstalling. But since that topic is old by now I doubt the author will answer in her topic.

Does anyone have a solution for this problem? I hope there'll be an update soon because quite a lot of people have this game error.

So, what I did was go to "Library" by opening Finder first and clicking on "Go" in the upper part of the screen. Pressed the "Alt/Option" key which made the Library map visible.

Then I went to the Cashe map in the Library map and I deleted a file called like 'unity....longdark or something'. Just search for 'dark' if you can't find the file in the map.

EDIT: You don't have to uninstall the game!

Now the game works again but I still can't play Coastal Highway because of the terrible lag