Asset files that end in .unity3d contain a bunch of project-specific data, which means they cannot be used on their own. You can create a stand-alone package of assets from within a given project using the editor, but only if you have the original project. Nobody should be giving out .unity3d files, because they aren’t useful without the rest of the project.
This really isn’t correct at all I’m afraid. “.unity3d” files are Unity web player files, from 2.0 onward. This is the equivalent of “.unityweb” files from the 1.x days. These can’t be loaded into Unity.
If you’re referring to “.unitypackage” files, there’s no issue with importing those into any random projects whatsoever; that is in fact what they are for.
If they are “.unity” files (not “.unity3d”), then they are scene files. You load them by double-clicking on them in the editor, or using “Open Scene” from the File menu.
That does not say much.
There are enough people building their players to the Asset folder although you won’t be able to build any further as long as the build is in there.
Hm… If I can’t load them in Unity, is there a way I could just run the files in my browser?
A .html page DOES exist, however it points to a .unity3d file which isn’t there. I can, of course, easily modify the .html file, but I don’t know which of the many .unity3d files to point it to.
Somehow, all of the files are needed in order to run the game.
if you don’t know which is the main file you will have to try each.
Question is, if you don’t know it, who developed it and are you legally entitled to reuse the content at all?