I see it as such: The Imperium of Man's many factions are going to be on the same side as the Space marine. I'm pretty sure theres going to be IG as NPCs to help facilitate the whole story and warzone etc. I'd like to see the "Legion of the Damned", traitor guardsman with Chaos Space Marines as well. The Sisters of Battle/Inquisition could make a special appearance as well, but basically (IMO), all of the imperial components would fall under the Space Marine "race". I doubt you'd get to play as anyone weaker than a space marine. All of the chaos components (traitor guardsmen, daemons) would fall under Chaos Space Marines, and I doubt you'd get or want to play as anything weaker than a Chaos Space Marine. It would be cool to see the Orks have internal conflict going on, a certain warboss hates another warboss, etc. The Dark Eldar could easily be a whole new playable faction, playable "race". The Tau could be a whole new playable faction too. Their size should be smaller than most if not all other playable factions, as in, their presence on the grand scale of the conflict would be the smallest imo. The Necrons I could see as being the most powerful NPC faction around. I could see the Necrons as like an alternative to the Tyranids. I want to see the Necrons represented as the most lethal, most powerful, and most dangerous force in the entire game, that can suddenly rear it's head and start threating all of the factions combined, even more dangerous than the Tyranid's NPC presence. If your faction's in a jam, try to "direct" all of your enemies into the tyranid meatgrinder, and maybe lead any attacking necrons over to the nid's territory some how. Let your enemies kill each other, eldar style! The Necrons are interesting though. Maybe, as a treat, you could be granted access to a Necron character. Or maybe, when even more planets are added, and once the Imperium of Man, The Forces of Chaos, The Tau Empire, The Orkz, The Eldar and the Dark Eldar get fully implemented, then the Necrons can actually get expanded enough for player access.
I don't see how IG, Demons, Sisters could even be considered as a 5th faction. IG and Sisters are aligned with the Imperium, as in ALLIES of the Space Marines. So the Imperium would have 2 factions versus Ork 1, Eldar 1, CSM 1. Do you seriously think GW will buy off on IG or Sisters fighting as their own independent faction versus Space Marines? IG and Sisters are clearly subfactions of the Imperium, and could be implemented as such in EC if Ork, Eldar, and CSM also receive another subfaction. If they do add IG as a SM subfaction, the only way you can do the IG is by having players control small squads of AI troops, as a Squad Leader. I'd be all for it though. Chaos Demons are aligned with Chaos Space Marines, so they're out as well as being their own independent 5th faction.
A unified IoM isn't feasible for several reasons. They would pull together too much of the player base (heck, part of the reason for introducing IG in the first place is to DIVIDE the Spess Mahreen population, not to bloat it even more), and their unit selection overlaps too much and would result in them displacing each others' roles. For example, nobody will ever pull a Predator once they have access to the Leman Russ. It is imperative that IG be independent. The easiest explanation I see for it is by using the fact that Space Marines are not meant to carry out long, drawn-out campaigns. After the war has waged on for a while, Segmentum Command starts insisting rather vehemently that the Imperial Guard be authorized to secure the planet and return it to the Imperium. Perhaps initially they focus their efforts on different parts of the planet in order to stay out of each others' way. After all, even though they're independent they're still not going to go out of their way to pick a fight. But as more of the planet is pacified and yet the Space Marines still refuse to leave, still refuse to turn over the remaining territory for the Imperial Guard to pacify, tensions rise, tempers flare, and suspicions take root... Also, IG doesn't need a 5:1 population multiplier if your regiment is reasonably well funded (ie you're actually deploying battle-hardened veterans instead of conscripts, and you're actually issuing them some of the higher-end IG gear). They aren't at perfect 1:1 parity, but they're adequate enough that all you really need is to adjust your play style and strategy to focus on their strengths and avoid their weaknesses (such as trying to make sure you've got Ogryns if you're expecting melee). Kind of like how a Magrider in Planetside 2 has the same armor as a Prowler but slightly lower DPS than a Vanguard. That should make it a horrible pathetic tank that never wins anything right? WRONG! The Magrider can hover, and that's worth way more than many people give it credit for. It proves itself out in the combat stats every day. There's more to balance than just HP and DPS.
People are still claiming that if SoB or IG are implemented, they HAVE to fight Space Marines or they can't be in at all. Anyone considered that they can be in without them fighting each other AND without them fighting together? If they add all other factions expect the ones who would be part of the imperium, you think they are going to make a huge 7-faction FFA in the midst of Arkhona? I don't think so.
Well, we could always put them on different continents. For example, if we have several continents and put 2-4 factions on each one (with some spare beachheads for cross-continent invasions) then basically each faction would only face 1-3 enemies the vast majority of the time, unless one of their neighbors pretty much conquers their entire home continent and starts taking trips across the pond. If the Space Marines and Imperial Guard have to go through 2-3 continents to reach each other, they would effectively never meet except for once in a blue moon (which we can easily brush off as a misunderstanding, or may result in a temporary alliance until they are separated again).
You could effectively even open up a warp hole and have 3 - 4 new factions of a fresh planet. To be honest I think people are getting too hung up on who must ally with whom due to lore, when essentially it makes sense to create an Inqusition faction with SoB as the main force, Deathwatch as elites and Greyknights as heroes. Let them hunt the Xenos, declare the Marines actions on the planet heresy (the Space Wolves will happily tell them to get bent) and fight for their own ideals, the Inquisition doesn't need to give a reason as to why it's there, it's the Inquisition to question them is to die. As for the IG, have them lead by independent royalty, hell have them declared heretics by the Inquisition, but they believe that they are in it for the greater good. The "why" is just about creative writing, I'd rather see them in the game than get stuck around the "why" of it. IG, SoB and marines fight each other all the time on the TT, and basically this is a game, just like the TT is so the precedent is already set.
Well, they have virtually confirmed that they will make something along those lines. The most relevant thing I can remember is Brent saying in one of those livestream things (the first one, I believe) that they plan to put all factions into the game eventually (if things work out) and that the growing number of factions is not a concern at all. An Inquisition faction could be done like that, but I'd hate it if all the elites were DW and all the heroes GKs. They would have to have SoB elites and heroes too, in the very least. There's also nothing speaking against DW heroes and Grey Knights aren't that powerful and could easily be just elites. You've said that rather nicely. Making a story that pits them against each other is easy, I honestly don't understand why some people keep raging at the very idea that various elements of the IoM could be fighting each other if they actually had a reason or two.
I wouldn't say that it's imperative, but it currently does seem like a good idea not to have them on the same team with Space Marines. On the other hand, they could easily be teamed up with the Sisters of Battle. I keep saying that and feel like I'm boring people with it. On the other hand, people seem intent to bore me with their same old shit, so whatever. ^^ They seem to supplement each other quote nicely for a game like EC. Examples... IG don't carry Multi-meltas around, but SoB do. IG don't have Jump Pack troops, but SoB do. SoB don't have a large variety of vehicles, but IG do. Etc.
I would consider that as a possible population balancing measure if one or both factions is underpopped. I suspect fans of both factions would prefer they at least be developed and launched separately though, so that neither one gets their unit selection reduced.
Best way to implement IG would be to either make them traitor guardsmen, or the most logical choice would be to have them assisting an inquisitorial faction thats opposed to all other factions due to some heresy/relics on the planet mumbo jumbo.
