RTF is a global modification that replaces all towns in the game.

whose skeleton are the fly models sitting on?
P.S. So, flies will be used instead of ghosts?

Added after 31 minutes

P.P.S. I read more and understood about "flies instead of ghosts"...

The flies are attached to the skeleton of the water elemental; the wings are attached to the streams of water coming out from under the mask, and the body is attached to the head and neck.