Hey everyone,
I've been lurking and collecting casually for a little while, and I've decided that I'm finally going to start to take the hobby seriously with this project; I'm looking to start a new chapter of Space Marines, playable as loyalists or Chaos. I'm going to use this post as a hub in which I'll be going in depth to develop both fluff as well as the modeling and painting process.
I already have roughly 10 Space Marines, 50 Imperial Guardsmen, 10 Orks and 10 Tau to play around with and convert my army with. I also purchased two new boxes of Space Marine troops (scout squad and tactical squad).
I like the fluff of the Salamanders, Iron Hands, Raven Guard, Mantis Warriors and Mentors, so I'll likely be taking one of their gene-seeds - not sure which yet. Alternatively, I may make the chapter a coalition of three prior chapters post-Istvaan Massacre, abandoned and left to survive on their own or presumed dead (
Mantis Legion, anyone?). I like the idea of bionic Marines but not necessarily of a fully mechanized army, so their limited resources and access to technology could play into this. The perceived betrayal on behalf of the Imperium would also lead to some harsh feelings among some of the free-thinking Marines, leading to a rebellious chapter which wouldn't, therefore, abide too strictly to the Codex Astartes. Perhaps their acquired knowledge of bionics and science - both thanks to the Iron Hands and Salamanders amongst them as well as their isolation on Istvaan V - could lead to the illegal/unethical (not that gene-seeding is too ethical in the first place) production of a unique gene-seed unknown to the High Lords of Terra. Their eventual escape - probably by hijacking a Chaos Battle Barge at the price of a large number of their men - would lead to them introducing themselves in some respect to the Imperium, while making it clear that they would fight for the Emperor (maybe there is still a majority of loyalists in the chapter) by showing them the corpses of the Chaos Marines and their newly-acquired ship,
but that they would not be shackled by the Imperium, largely due to their abandonment, of course. This would justify them playing as Chaos or Loyalist, I think.
As Theo suggested, I would probably play them as Iron Warriors when I go Chaos, but I do want to overhaul the color scheme. Here's a rough idea: Mentors scheme (green and white) with hazard stripes on a shoulder (Iron Warriors), and black arms/silver fists... I'm afraid that this would look way too busy, though. Alternatively, I could replace the green of the mentors with black, bring it all the way down their arms and maybe have white helmets. I'm not entirely sure... I'm not totally convinced by the picture I attached. Note that the grey on the feet, hands, wrists and shoulder trim is meant to be silver. The soft armor may also be dark grey rather than pale gold-ish. Also don't forget one shoulder with hazard stripes. I like the idea of hazard-striped weapons, as well. see the attachment below
The pink should be hazard stripes and the half of his face that is black should be yellow. The B&C painter wouldn't let me change it without altering half of the marine.
As for the list, for now I'm thinking lots and lots of veterans... Probably a bunch of sneaky little vets who are used to infiltrating and taking down battleships and such.
. If your looking for doing a borderline loyalist/chaos army you might consider doing a splinter/descendant chapter of the iron hands. With all the bionics they could also be iron warriors if you go with a steel grey color scheme. Play them as loyalists of your own chapter one game then play them as an offshoot of the iron warriors when you feel evil 
. Plus the imperial guard guys could be traitor guard/ mechanicus allies either way.
