I am myself an Urban War player, I play both Triads and Galdiators, now it's an easier system, by easier I mean quicker, games can be over in as little as a half hour.
And each faction is like the 40k races both similar and iduvidual, the Gladiators and the Junker are able to be allied together, kinda like ancient Rome, but the Junkers are convict legionarres. Triad and Vasa are able to ally, the Triads are as their namesake, a criminal organisation but now and again ally with the VASA, who happen to be the cops!, and are just fun.
But the 'sea slugs'; Koralon are unable to ally because they are doing the nid thing, devouring the enite planet in a different way, the syntha are Necrons but more fleshy and naked with some models(Especially the naked female model) and the viridians are the future coroporate american military.
also just a few other fun things; I have seen a koralon army with converted Krootox as Broodlords, I have also seen nids being mixed with the normal brood, the gladiators have big attack pigs, basically angry pig men with swords attached to their arms.
VASA= Communists, futuristic communists
TRIADS=Asian Gangster clans with hire sumo bodyguards
JUNKER= Rome all over again
Gladiators= as above but with pigs, which happen to be called pit beasts
KORALON= Sea slugs from hell
SYNTHA= Necrons and the Adeptus Mech mixed together somewhat
Viridians= Armed humans fighting for money.
Another short thing, the game is based on a planet called Iksandria, once the capital of a interstellar empire but with its revoulutionary leader, forget his name' it shatters into a civil between the VIRIDIAN, Ironglass (Junkers/ Gladiators) and VASA war with the recent additions of the Triad, Syntha and Koralon who have begun to emerge as dominat powers on Iksandria admist the rubble of city blocks these faction vie for dominace of Iksandria.
Overall it's a good game to play, but 40k is still my first love/addiction.