The beginning of this year, Forge World released a set of experimental rules called “Zone Mortalis”. These rules can be used to simulate close quarter battles in places such as underground bunkers, underhives, mine works and space hulks. Zone Mortalis games are intended to be played with lots of separating walls and such like and alter the way certain weapons work, for example blast weapons and template weapons can re-roll to wound rolls to represent shrapnel and scattering weapons detonate on walls rather than travelling the full distance. There are also rules for deep space where some weapons become rending.
This makes games far more lethal and restricts the structure of your army – afterall what use is a Rhino when you can only get it down a single corridor? It also allows you to utilise the Forge World boarding weapon upgrades which are intended for this type of fight.