Greetings
I have idea how to improve this mod.
1.Space Marines recruiting. It's a bit odd, that you can recruit space marien like a simple guardsman, just a bit expensive. So i propose not to purchase marines, but to manufacter them using space marine recruits (buys at market) and gene-seed (in early game you will have limited stock of them, or can extract from space marine corpse, in late game you can buy it from the market ). That limits space marine numbers for early games and make auxilia more useful.
2.Space marine training and armor. Increse starting MeleeSkill, max Health=150 and max Stamina=200. And make armor stamina dependent. For example standart armor gives -60 to stamina, so only expirienced troops can wear it and use it efficiently. So rookies have to wear scout armor (no stamina penalty), assault armor (less stamina penalty), devastator armor (becouse they don't need high mobility). More expirienced troop vill wear standart armor, veterans - terminator suits, etc. This will be lore wise and bring some gameplay variability.
3.Special bolter amunition and bolter variations. Adding some explosive ,chemical nad armor piercing ammo for bolter will make bolter great again. Also some variants - Staler pattern with precise accurate shot, variants with high capcity clips and high rate of fire, combi-colter that can shhot nolter ammo or something like plasma, flame, grenades, etc.
Points 2 and 3 sound great, but Point 1 is a little iffy to me. The idea of regular Guardsmen wiping out entire ships full of Chaos Space Marines seems kind of weird and lore-unfriendly. Plus, in my opinion, Space Marines are more desirable to play as rather than squishy normal humans, though I can understand wanting to play as a faction that you can relate more to, and aren't as Mary Sue-ish as the Space Marines. Not to mention, playing as Guardsmen really limits what weapons and armor the player has access to, relatively speaking.
This is most obvious in terms of armor, where the Guardsmen get only flak and carapace (Stormtrooper) armor. Maybe power armor, if there are Inquisitors involved. Space Marines on the other hand get a ton of choices, from Scout to Tactical to Terminator, and maybe even MK I to MK VIII armor if bulletdesigner is feeling really generous, and hell, let's throw in Primaris Marines and their equipment as well.