I found a solution. After downloading the file and unzipping it, right click on it and choose "Show Package Contents".
Then go to "Contents > MacOS". There you'll probably find a file in document format.
Now, open terminal and type "chmod +x ", and drag and drop the document in the terminal (which should fill the path)
You will be able to open the game after running the command
If it shows that the developer cannot be identified or something, go to "Privacy & Security" in system settings, scroll down and click open anyway.
This works for most of the apps affected by the issue
Idk if you still have this problem, but make sure that you have a space between the +x and the filename or else the terminal will think that you are trying access a folder called "+x" which obviously doesn't exist.
After you do this it should work (an indication of this is the document icon of the Jelly Drift file in the finder window becoming a terminal icon - a black rectangle with green on it)