This template is used when an actor from an original Keen game is used unchanged in a mod. This can happen when only some of the game's actors are changed.
The template should be added to the actor image from the official game. If any of the parameters are different (e.g. in the mod the actor is no longer lethal but is in the original game), then the image should be reuploaded as a new page and the same description applied as with any other completely new mod actor. OriginalActorInMod template is missing Game parameter.