Board Thread:General Discussion/@comment-4129195-20150218112353/@comment-452-20150218141505

Wikia Staff regard screenshots as being the property of the creator of the game. (Unless the creator of the game says otherwise)

You can't force the other wiki to add the description and license themselves, and Wikia Staff will not insist upon it either, or take the images down.

What you can do is add "Originally uploaded to X wiki" yourself, and hope that the users there start also adding it.

You can also link them to http://community.wikia.com/wiki/Wikia_Community_Guidelines, which says
 * Attribute fairly
 * Wikia believes in the open source movement. Creating content that can be shared and enjoyed by others is a big part of what we do. But, that doesn't mean we should ignore other's rights. Whether you use text, or images under license, with the author's permission, or under "fair use" guidelines, it's always polite to give the proper attribution.

Which might convince them to do the polite thing (even though they are not legally required to).

If you can get a public statement from the creators/publishers of the game that screenshots are the property of the players, and you when you uploaded the image originally you indicated that it was your property, then it's a different story altogether.