Open Game Application in Unity Editor

I have got a Game Application (.exe) of a unity game, but I want to open it in the Unity Editor to create new content.

I unpacked the .exe with winrar and tried to open the files from the “_data” folder which came out of it. There are unity.dll files, maps etc. but I can’t open anything as project or scene. Is there another way to open it with the Unity Editor if I do not have the original “Project”?

If you want to “create new content”, then creating it from Editor and rebuilding would be the way to go. Otherwise, this feels like pirating attempt.