As this product is yet to be released, information is based on official Games Workshop propaganda from their website and social media accounts. Information protein in this page might not hold true to the final product.
Unlike the original Necromunda wargame, with emphasis open ground populated by tall, multi-floor structures with lots of barricades and walkways, the battleground of Hive Wars is a series of rooms and corridors, with bulkheads serving as doorways, similar to Space Hulk. The game will come with a set of large cardboard tiles for modular rooms and corridors, and plastic bulkheads, barricades, loot caskets and terminals.
Where the old Necromunda bok set was open-ended with the gangs you play out-of-box, Hive Wars seems to be set-up with prefab gangs — Ironlords Goliath gang and the Carrion Queens Escher gang — with their own names and Fighter Cards. Fighter Cards are index cards noting combat and weapon statistics, skills and wargear. The game seems to be also set-up to allow for personalized gangs, with highly modular figures and blank Fighter Cards.
The game will introduce Tactic Cards that are "used to represent the myriad tricks and schemes employed by the gangs." There are general Gang Tactic Cards usable by any gang, along with gang-specific Tactic Cards.
Along with the usual 6-sided dice, specialized dice are: Scatter Dice, Firepower Die, and the new Injury Dice. The normal "d6" dice feature an Eagle-Skull icon in place of the 6-side. The Scatter Dice is the same as the old version. The Firepower Die is similar to the old Sustained Fire Die, but with bullet and bullet-holes icons. The Injury Die shows icons of a bracken bone, a medical cross with blood drop, and a skull. The dice set comes in black with yellow markings, and yellow with black markings.
Previews of Fighter Cards show additional statistics unseen since the early days of Warhammer: 40,000. Long since absorbed into the Leadership stat by second edition Warhammer 40k, Cool, Willpower and Intelligence represent different ways to deal with physiological and technological problems. Where Leadership used to be about commanding fighters and keeping them in battle: Cool allowed fighters to keep their nerves and resist effects physiology (fear, confusion, etc.); Willpower allowed fighters to resist effects of psionics; and Intelligence allowed fighters to deal with technical issues like clearing jammed ammunition, disarming traps and security measures, and knowing how to work advanced or specialized hardware.
The Reference Sheet and Blank Roster previewed on the official site make hints at a number of small and large rule changes from the original rule set. Actions are spelled-out, with whole new actions available. Fighter can now open locked doors and loot caskets by force (Strength check) or by skill (Intelligence check). Flesh Wounds reduce a fighter's Toughness down by 1-point, instead of Weapon and Ballistic Skills. The old blocky To-Wound Table is replaced by a simplified Strength vs Toughness Wound save roll based on Strength being equal to (4+), greater/lower than (3+/5+), or twice/half as much (2+/6+) to the target's Toughness.