The armiesI controlled the Traitors and my two friends took joint command of the Loyalists, playing the roles of Rogal Dorn and Sanguinius.
I put together the armies using a few different army lists and some made up stats. I used the standard Steel Legion list for Imperial Army. I used Simulated Knave’s Horus Heresy list (v0.3) for the legions. I used a titans list that I have got saved on my hard drive (probably been superseded now). It was War Gryphons v3.18b.
The traitors had about 7,500 points and the loyalists about 7,000 (plus strong defensive positions).
I made up some stats for the primarchs. They were DC2 (but behave as infantry rather than war engines), Armour 4+ (reinforced), Fearless, Inspiring, Invulnerable save, Leader. Rogal Dorn and Fulgrim were also Supreme Commanders. CC and FF were between 2+ and 4+ depending on the primarch. I also gave them all 3 extra macro weapon attacks in assault, which I split between CC and FF depending on who it was (ie Angron’s were all CC, while two of Magnus the Red’s were FF to reflect his psychic powers).
Orders of battle are below:
LoyalistsRogal Dorn (in command)
Sanguinius
Jagathai Khan (off the board, flanking)
Adeptus Custodes in thunderhawk
Imperial Fist dreadnought company
Imperial Fist fire support company
Blood Angels assault company
Blood Angels assault company in thunderhawk
2 x White Scar biker companies
Warlord titan
Reaver titan
2 x Imperial Army infantry companies
Leman Russ company
Baneblade
Shadowsword
Storm troopers in Valkyries
Artillery company
Hydras
Sentinels
Thunderbolts
TraitorsFulgrim (in command)
Angron (he deployed inside the city walls with a company of his World Eaters. A static shield bubble means nothing to him

).
Magnus the Red (in a Stormbird)
2 x Emperor’s Children land raider companies
2 x Emperor’s Children land speeder companies
2 x Emperor’s Children Whirlwind companies
2 x Emperor’s Children Fellblades
Emperor’s Children tactical company with predators
Thousand Sons Terminators
Thousand Sons fire support company with dreadnoughts in a Stormbird
Imperator Titan
4 x Warhound titans (two in a pack)
2 x Thunderbolts
World Eater berzerkers (with Angron in the city)
World Eaters tactical company (deploy via drop pod)
12 x lesser daemons
Greater daemon
Here are some more shots of the deployment:

Imperial Army storm troopers deployed at the rear, awaiting orders.

More brave men of the Imperial Army man the defences, and try not to worry too much about the massive gap in the front wall.

Rogal Dorn and his Imperial Fists, commanding the loyalist defence.