In the early 2000, Palladium was experiencing a downward trend, so to try to offset decreasing sales, Palladium continued creating new settings; as a result the brand new game Rifts Chaos Earth (2003), a prequel to Rifts, was released and soon supplemented by a few sourcebooks (2003).
Chaos Earth was originally intended to be a parallel dimension to Rifts where the massive deaths were caused a minute after midnight when the released Potential Psychic Energy (P.P.E.) was magnified. Everything that happened in Rifts happened on a smaller scale in Chaos Earth. In Chaos Earth, most of humanity survives and has to fend off the supernatural. This game style can be played in Palladium's Nightbane series. Sometime after its original press description in an early Rifter, the game changed from a parallel dimension to Rifts history, perhaps due to the level of interest in Rifts' past. Now in the Palladium Megaverse, the Chaos Earth setting is the period in Earth during which the rips in space-time known as rifts ripped apart mankind.
Chaos Earth gives players a chance to play in a world somewhat more recognizable than the world of Rifts. Monsters are only starting to appear and there the forces of humanity are still trying to hold on to the civilized world that Earth had been, as opposed to Rifts where characters live in a world where violence and horror have been commonplace for centuries.
Sourcebook One:Creatures of Chaos, first printing September 2003
Sourcebook Two:Rise of Magic, first printing November 2003
Resurrection has been on pre-order since the first half of 2015 announced in February and in March still maintained as having a "spring release" which it missed, not having come out in April or May. By late June July was declared as being off the presses for August's Gen Con Indy.
First Responders has been on pre-order since as early as 18 June 2012
NEMA Mission Book 1 is not listed as a sourcebook and has been on pre-order since as early as 13 May 2012