While Grimdark future is a really cool ruleset that captures the 40k spirit. It is also an intentionally loose ruleset in some parts. Rules for stuff like cover saves and more are fairly basic, to the point that they actually force you to make some house rules. This post catalogues the house rules I have added in my games of Grimdark future. The ones marked with “!” are the one I find the most important for smooth games. The others are to get more immersion and classic 40k feel.
Cover and line of sight
I have borrowed the cover definitions of earlier editions of 40k (3rd / 4th) and tried to clean those up. These rules put much less demands on LOS-blocking terrain, letting those pretty ruins and forests actually play an important part on the table.
!Cover terrain – Ruins, forests etc. blocks LOS through them, up to the height of the terrain outline. Models can see maximum 6″ into area terrain. If a model is inside cover terrain, it benefits from cover.
A model counts as being in cover terrain if the line of fire crosses the base of the area terrain.
!Being in cover – A model counts as being in cover if any part of the model or base is obscured from all firing models in the enemy unit.
A unit that has at least 50% of their models in cover counts the entire unit as being in cover.
Barely visible – If only a tiny part (less than 10%) of the model can be seen by all models in the firing unit, the cover modifier is increased to -2.
Banner poles, pointy swords, aerials and other tall and impractical scenic bits do not count for LOS.
City fight / terrain additions
One of my favorite parts of 40k is city fighting. There is no secret that the Vogen campaign has a special place in my heart. As such, I have added some more terrain rules to make terrain play a bigger part in the battle. I have also felt that difficult terrain is too impactful, restricting any unit to only 6″, which makes it tough to use much of it. Making it less punishing allows me to count much more terrain, such as ruins and barricades as difficult.
Elevated terrain – If there is a ladder, stairs, sloping hills, elevator, convenient boxes or other means of scaling the elevated terrain, use normal movement for moving vertically.
If the elevated terrain is steep and has to be climbed, it is additionally counted as difficult terrain.
Certain units cannot climb or use ladders, for example vehicles and horses. Use common sense. If the player can explain how it can be done convincingly, then it is allowed. (driving a vehicle full speed off an elevated roadway to smash into the second story of a ruin for example)
Terrain classification for unit type – some terrain might be dangerous to only some kinds of units. Ruins are dangerous terrain for vehicles, jet bikes and jump packs, but count as normal cover terrain for infantry. Tank traps are impassible for ground vehicles, but cover terrain for infantry. Razor wire is difficult terrain for vehicles, but dangerous for infantry and cavalry. Agree with your opponent what terrain counts as what for the involved unit types. (use 40k classification for unit types)
Strider – Additionally gives re-roll to 1 dangerous terrain roll per activation
Rushing in dangerous terrain – Units rushing in dangerous terrain re-rolls successful dangerous terrain tests
Difficult terrain – Units moving in difficult terrain can maximally move their normal move + D3″
Fortified terrain – Purposeful strongpoints like bunkers, trenches and fortified concrete buildings give a -2 cover modifier.
That is it for now, but reviewing the old city fight codex, there are other thematic rules like benefits of elevation I will probably add once the city fighting heats up again