Warsword 20T

In the GrimDarkness of a long time ago in a galaxy far, far, away, there is an unfunny writefag trying to fix complete grimderp.

Not Space Marines

Followers of new-age space jesus. Through his teachings, believe that they are the natrual evolution of humanity into a better state. As such, they are looking to spread their empire into space as far as they can. They believe that anything that even remotely threatens humanity, such as the normally non-confrontational Takun empire, should be destroyed before they can restrict humanity. This actually started most of the TaKun's hostilities with other races, although the man in charge of the chapter that initiated the attack believes it was entirely justified.

Not Chaos Forces

Like their normal counterparts, believe in the advancement of humanity. However, purity has been forsaken in the pursuit of becoming competely perfect and indestroyable. They will not consider themselves completely advanced until they have killed off anything in the universe that isn't them or at least attempting to perfect themselves through the chaos deities. To further drive in the SPAAACE JESUSSSSSS references and to save our asses from the lawyers, there are 7 chaos gods, each for a sin. NotKhorne and notSlaneesh are still responsible for wrath and lust, while notNurgle is a representation of gluttony (disease consuming all in it's path) and notTzneech is a representation of pride (constantly changing oneself and the world around them in order for it to be perfect idk). There could possibly be minor rule variants for what your units were before turning to chaos, but they're mostly the same.

(I'll admit I added the last part in because the lack of anything chaos besides space marines is stupid to me)

Hyuumanz

Human society originally spread out across the stars to help decrease overpopulation, and then they ended up accidentally pissing off every single force in the galaxy. They butt heads with the not space marines on occasion because they aren't anywhere near to the level of perfection the not space marines are at, and in their piddly efforts to survive, occasionally piss them the fuck off. However, the earth is neutral ground, since it is the birthplace of humanity.