Combat in an environment as cluttered as the ruins of a hive city can get very close and desperate, as squads come under attack from hidden foes or attempt to drive their enemies from a defended position. Orks in particular favour and excel at such close quarter fighting, though renegades have had to become adept in order to conserve ammunition and many guardsmen are trained to use weapons like shotguns to defend themselves.
Though I've kept as closely to the existing system as possible, the use of squads means that many more models are likely to be fighting at any one time. This forces a degree of simplification on the system to avoid the situation of 2nd edition 40K where combats could take hours to resolve.
I've also altered the "scope" of close combat to include close range firepower as well as actual hand-to-hand fighting. This was something I've always thought should be the case and simulates the effects of troops firing upon charging enemies or blazing away with pistols as they close in.
Except where noted otherwise below, combat is fought exactly as per the rulebook.
EXCEPTION 1: COMBAT SCORE MODIFIERS
EXCEPTION 2: GANG UPS
In order to keep the amount of dice rolling and mental arithmatic to a minimum, I've simplified the rules for ganging up. Instead of the rules given in the rulebook, use the following system:
All models attacking one enemy are treated as a single entity and make a combined attack. They fight with the total number of attacks the group posesses and have a WS equal to the highest amongst them plus one for each combatant. When determining highest initiative, the group counts as having the highest value amongst them. This aside, all other bonuses are added for each model that they apply to.
All hits must be distributed evenly between the combatants, starting with the highest I. Each model must also adhere to the rules regarding allocation of hits to weapons.
EXCEPTION 3: WEAPONS
Instead of models being allowed to use pistols or hand weapons in combat, a model may use ANY weapon it is armed with (ie, has in it's hands at the time). Missile weapons add their "to hit" modifier for short range to the firer's Initiative. If a model using such a weapon wins combat, one hit MUST be with the missile weapon per point of "to hit" modifier it has - eg, a model using a bolt pistol MUST assign their first two hits to the bolt pistol. Subsequent hits are divided equally between all weapons used as normal.
Heavy Weapons... only heavy weapons with Sustained fire may be used and even these may only be used in the combat phase that the wielder is charged. Wielder counts as having the highest I automatically and may add +2 to his combat score for every sustained fire dice the weapon has. All hits are with the heavy weapon itself.