False Dawn is set a number of years after the events of Quake 4, where you assume the role of the Most Unexceptional of a new breed of soldier, the Stroggified Marine. You can go where no regular human can and have been called upon to save humanity from the threat of a mysterious new super weapon developed by the vicious Strogg!
False Dawn is an excellent, if brief user-made campaign! Both the hub-based level design and the locational weapon system should've been part-and-parcel of Quake IV when it was released, though I'm glad somebody finally got around to implementing these features. The end result is a game that plays not entirely unlike Quake II, and I don't need to remind anybody about what a great game THAT was.
If False Dawn has a flaw, it's the Sikkmod graphics suite. Its options do a fairly poor job of concealing Quake IV's aged textures, and the fact that they suck up way too much GPU memory in the process only makes things worse. Call me spoiled, but I don't much care for the idea of playing a nine-year-old game with anything less than 60+ fps the whole way through. Unless your machine can handle the strain that Sikkmod puts on it, you'll save yourself a lot of headaches if you just all of its features off; you'll be left with a game that's graphically identical to base Quake IV, which still looks decent even in 2014.