I'm having the same issue! I've tried all the recommended solutions with no success.

Same issue :C

DITTO

same!!! try to install on my new mac, not OPENING.

+1.

+1

This worked for me:
1) On your Steam Library list, if you click on PLAY for Don't Starve and you will encounter the error message indicating the file is damaged and should be moved to trash, click on the cancel button to close that window.

2) Instead, go back to your Steam Library list, right-click on Don't Starve > Click on "Manage" > and click on "Browse Local Files"; this will open up your installation folder.

3) Right-click on the donotstarve_steam app > select the OPEN button; this will provide another error message indicating the following:
"dontstarve_steam is damaged and can't be opened. You should move it to the trash."

4) On that error message, click on the OPEN button. This will force the Mac OS to launch the game successfully. Once you are able to successfully launch it once this way, you only need to click on the PLAY button on Steam to launch it going forward.

+1

Originally posted by tengalaxies:

This worked for me:
1) On your Steam Library list, if you click on PLAY for Don't Starve and you will encounter the error message indicating the file is damaged and should be moved to trash, click on the cancel button to close that window.

2) Instead, go back to your Steam Library list, right-click on Don't Starve > Click on "Manage" > and click on "Browse Local Files"; this will open up your installation folder.

3) Right-click on the donotstarve_steam app > select the OPEN button; this will provide another error message indicating the following:
"dontstarve_steam is damaged and can't be opened. You should move it to the trash."

4) On that error message, click on the OPEN button. This will force the Mac OS to launch the game successfully. Once you are able to successfully launch it once this way, you only need to click on the PLAY button on Steam to launch it going forward.

This worked for me too. Thank you so much!!!

I have tried every possible fix, but I'm still not able to play. The above suggestion would have worked if it wasn't for my mac being enrolled by the company I work for. The company has set "Open untrusted apps via Finder" to "Disallow" through a security policy. Of course the solution is to use a different computer, but I got rid of my own M1 mac when the company provided a developer specked mac and ensuring me that I would be allowed to use it without limitations even for personal use. They later introduced the enrolment. My point is that not everyone can override the security policy on their system, but we really shouldn't have to in the first place.
Klei developers: The real issue seems to be that installed files are changed after signing. This in turn makes Mac OS treat the application as a threat. Please look into how you sign the build so that it's treated as a legitimate app.

Originally posted by KnightShade:

I have tried every possible fix, but I'm still not able to play. The above suggestion would have worked if it wasn't for my mac being enrolled by the company I work for. The company has set "Open untrusted apps via Finder" to "Disallow" through a security policy. Of course the solution is to use a different computer, but I got rid of my own M1 mac when the company provided a developer specked mac and ensuring me that I would be allowed to use it without limitations even for personal use. They later introduced the enrolment. My point is that not everyone can override the security policy on their system, but we really shouldn't have to in the first place.
Klei developers: The real issue seems to be that installed files are changed after signing. This in turn makes Mac OS treat the application as a threat. Please look into how you sign the build so that it's treated as a legitimate app.

I agree, and I can't do the above solutions because it doesn't show up in my finder.

Here's the procedure that I have used with other programs, including other Steam games. . .
1. Try to start the game, get the "damaged" message. Cancel that dialog--obviously, not using the trash-your-game button!
2. Go to your Mac's System Settings program and find the Privacy & Security tab. Then scroll down until you find the message that Don't Starve was blocked. There's a switch you can flip that will enable it to run.
3. When the program runs you'll get yet another "damaged" message, but this time there should be a button to "open anyway". Once you get the program started, these noxious messages should never appear again.

However. . .

The bad news is, after going through all of this, the program launched and then instantly died on my M2-based system.

Originally posted by tengalaxies:

This worked for me:
1) On your Steam Library list, if you click on PLAY for Don't Starve and you will encounter the error message indicating the file is damaged and should be moved to trash, click on the cancel button to close that window.

2) Instead, go back to your Steam Library list, right-click on Don't Starve > Click on "Manage" > and click on "Browse Local Files"; this will open up your installation folder.

3) Right-click on the donotstarve_steam app > select the OPEN button; this will provide another error message indicating the following:
"dontstarve_steam is damaged and can't be opened. You should move it to the trash."

4) On that error message, click on the OPEN button. This will force the Mac OS to launch the game successfully. Once you are able to successfully launch it once this way, you only need to click on the PLAY button on Steam to launch it going forward.

This worked for me. Thank You!

This method worked for me. But I'd like to clarify step 3, after you move it to the trash, move it back into the folder, then try to open again.

Originally posted by tengalaxies:

This worked for me:
1) On your Steam Library list, if you click on PLAY for Don't Starve and you will encounter the error message indicating the file is damaged and should be moved to trash, click on the cancel button to close that window.

2) Instead, go back to your Steam Library list, right-click on Don't Starve > Click on "Manage" > and click on "Browse Local Files"; this will open up your installation folder.

3) Right-click on the donotstarve_steam app > select the OPEN button; this will provide another error message indicating the following:
"dontstarve_steam is damaged and can't be opened. You should move it to the trash."

4) On that error message, click on the OPEN button. This will force the Mac OS to launch the game successfully. Once you are able to successfully launch it once this way, you only need to click on the PLAY button on Steam to launch it going forward.

To allow untrusted files on a Mac, try to open the file first, then navigate to System Settings > Privacy & Security > Security and click the Open Anyway button to create an exception for the file