The Redfaction FS:FPS project had a lot of pre-design work done, and in fact work on some models and levels. The project itself didn't survive more or less due to the lack of interest in the game, the same happened with most Tribes:Vengeance mods. In the case of RF with Unreal Tournament 2k3 coming out, and geomod not being as effective as hoped, tons of projects changed engines.
Needless to say Plasma, IceFire, and myself had a plot outlined loosely based off of Plasma's fanfic "Phantoms." You played as a GTI operative at the height of the V-T war, dealing with insurrectionists in Beta Aquilae, the Vasudans, as well as some of the GTI's darkest secrets. (*cough* Shivans *cough*) There were some cool concepts modeled such as Bobboau's "Shivan drone" (a hybrid of Vasudan and Shivan) and even some human-Shivan experiments. (though the latter are... well... let's just say ETAK was a bit nastier of a concept than at first implied)