Flash Flood rules

Today, I've got some rules for a “special event” which I designed for another game of the Ichar IV campaign.

One of the scenarii, using the Combat Patrol format, was supposed to take place in the Hive’s sewer system. The Imperials were trying to place charges into a brood-nest hidden within the sewer system. If the Imperials failed then the ‘Nids would gain a fourth stratagem for the next game: Sewer Rats.

To add a level of randomness to this game, it was decided that the sewer systems were badly damaged and that flash floods frequently occurred. I was thus tasked with coming up with rules for such an event...

I'm only posting the rules without a full scenario because they are actually usable regardless of the mission you pick (adding a twist to the events).
I've added a few comments (between brackets) here and there to help you understand the reason behind some of the rules and thus use them more easily. But the translation from french proved harder than I anticipated and there may still be some parts which are not clear enough. If that's the case, please let me know, I'll edit accordingly.

Without further delay, here are the rules as we played them:

[You can have the pdf version (without the additional comments) here (right click and "save as"). ]


++ FLASH FLOOD RULES ++

Decide prior to the game where the flood will originate from. [A corner of the table does the trick nicely. If you pick a central point, then you can cut the resolution of the flood effects in two, getting one half of the table done before dealing with the other.]
It is important to note which parts of the system will remain out of reach of the flood (gantries, etc...).
Grates, sluice-gates and the eventual cave-ins in the system will count as Impassable during the flood (even if they only count as Difficult terrain during the rest of the game).

The flood may occur at any moment starting with turn 2. On turn 2 the flood occurs on a 6+, on turn 3 on a 4+, on turn 4 on 2+ and it takes place on turn 5 if it didn’t earlier...

When the flood occurs roll for each model separately against their Strength, starting with the furthest from the origin point of the flood (in case of doubt roll a d6 to decide which model must test first), if the roll is failed then the model looses its footing and is carried away by the rushing water. [It may seem counter-intuitive to start by the model furthest from the flood's point of origin, but it has its own game logic: "bumped" models --see below.]

The model is carried away by 1d6". If the result of the roll is a 6 then it is carried for another d6", if that result is another 6 then roll another d6, etc... Roll until the model either stops or comes into contact with Impassable terrain. [This represents the tunnel-fighter trying to gain hold of something to stop being carried further by the torrents of water.]
If the corridor turns, then the model's movement follows the twists and bends. If a corridor branches, then roll 1d6 to decide along which branch the model is carried away.

If, while carried away, a model comes into base contact ("bumps") with another one, on a 4+ the "bumped" model is knocked off its feet by the other and is carried away by the water. [This means that a model which was once carried away and succeeded in stopping its movement can still be carried away further because one of his squad mates bumps into him --and is the reason why you should start with the model furthest from the flood source.]

All models which loose their footing and get carried suffer a S1 hit without save, +1S for each full 3" moved (hence S2 for 3" to 6", S3 for 6" to 9", etc...). A model which is stopped by Impassable terrain suffers an additional S3 hit. [This represents the fighter hitting the walls, pipes and grates while fighting to stop his momentum and the possibility that he's knocked-out or even drowns.]

Once the flood took place, every part of the board which was flooded counts as Difficult terrain for the rest of the game.

It is evident that the flood will cause chaos and force the majority of the models to break unit coherency.
All models out of coherency must use their maximum movement to restore unit coherency and cannot do anything else but run/fleet during the shooting phase. They may however fight in CC if charged (but can't charge).

A unit which has less than 50% of its (surviving) members in unit coherency is scattered and cannot act normally (they remain only able to move towards their nearest squad mates by their maximum movement, run/fleet and fight if charged).
Once part of a unit has lost the scattered status, it may act normally, but all the members of the unit still out of coherency will continue to be only able to try to join with their squad mates.

If a single model or a scattered unit can't restore unit coherency without having to go within 1" of an enemy unit/model then 2 possibilities arise:
1) if the enemy unit is itself scattered, move the unit/model by its full movement "through" the enemy models, any model which could not go fully through the unit and more than 1" away by the end of the shooting phase instantly dies. Once all the models have been moved, fight a single round of CC considering all models for both units were engaged. Remove casualties as usual. [This represents the men/xenos fighting their way through the relative opposition of enemies without coordination.]
2) if the enemy unit is not scattered then move the models into base contact with the enemy unit and fight a round of CC as usual, the enemy counting as having charged! If the model/unit survives the round of CC then leave it locked in CC with the enemy unit. On the enemy's turn another round of CC will be made and if the unit/model survives then you'll be allowed to break combat on your movement turn without any penalty. [This represents the men/xenos fighting their way through organised opposition.]

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As you can guess, these rules transform the game into pandemonium as soon as the flood occurred. They were very funny to play with and we’ve used them a few other times since then with great pleasure…

The fact that one of my friends, the one who’s tasked with all the terrain building for our campaigns, built a beautiful modular sewer system table for us played a big part in us re-using these rules. But you don’t really need to build a table just for this, you may simply build “corridors” by placing rectangles of cardboard on a table and with a bit of imagination you’ve got a playable sewer system table ;)

What I like the most about these rules is that, for at least 2 turns after the flood, the game feels very different to play, emulating quite well the complete anarchy that would result in such a situation.

I must recommend however not to play it with a format bigger than Combat Patrol, because the model by model nature of the flood rules themselves would become to heavy to manage if you’ve got more than a few squads each to move around on the table.

I hope you’ll have as much fun with these as we did!

Pursuit - A 40K mini-game

For my first post, I'll present you with a mini-game which I designed for my group's Ichar IV campaign, we replayed the events of the Kraken Invasion, culminating with the defence of Hive-city Perseus (which was France in the GW official worldwide campaign). We used most of the games available to us in this campaign. We started with a few games of BFG and Space Hulk to reproduce the arrival of the Hive-fleet and the breaching of the Imperial blockade, then Epic to reproduce the advance of the 'Nids force towards the Hive-city, then we used 40K for the cityfighting, which would decide the ultimate fate of the Hive-city, and Necromunda to play the civilian's escape in face of the xenos invading the Hive.

To decide who would get the "initiative" in the first 40K game, I designed this mini-game called "Pursuit" in which a squad of Space Marine Scouts stumble upon the vanguard of the Tyranid advance and must escape to inform their command. If the SM player wins, the Imperials will be warned and gain a few advantages in the next game, if the 'Nids player wipes out the Scouts, then the xenos will fall upon unprepared lines.

Just one last thing before proceeding with the rules themselves, this mini-game was written with 4th edition, and, while 5th removed the notions of "sizes" for buildings (etc...), I've decided to keep them in this mini-game for ease of play. As you'll see the sizes are quite useful for the pursuit and movement phases, you'll just have to ignore them in the shooting phase and use TLoS to update the mini-game to 5th ed. ;)

EDIT: If you'd rather download a .pdf version than read it on the blog, or to print it and have it handy to try the mini-game, then you can download it here (right click and "save as").

+++++++++++

The Story:

A Scout Squad on bikes has located the Tyranids advancing through a ruined part of the city. But they couldn't withdraw unnoticed and find themselves chased in the ruined streets by Gargoyles. If that was not enough, they ended up within a spore-minefield... They must escape to make their report or the Tyranids will fall upon unprepared Imperial lines!

Lists:

Space Marines: 5 Scout bikes (without frag grenades/melta bombs)

Tyranids: 12 Gargoyles and 4 Spore Mines clusters (3 frag mines each)

If the Scout Sergeant is upgraded to Veteran Sergeant and takes additional equipment from the Arsenal, then the Tyranid player gets 3 additional Gargoyles.

Table:

This game takes place on the length of a table at least 60" long. One of the table's small edges will be the "Arrival". Place as much City terrain as possible on the table, leaving a sinuous "street" along the middle. Try to keep the terrain type balanced, putting the same number of each different terrain types (size 1, 2 and 3).For this game all ruined terrain pieces of size 1 and 2 are considered Difficult while ruined size 3 and intact buildings are Impassable. The Gargoyles however are simply flying over size 1 terrain and thus don't consider it Difficult.

Deployment:

The squads don't have to keep unit coherency for this game.The Scouts are deployed anywhere but at least at 48" of the "Arrival".The Gargoyles are deployed according to the same conditions, but must also be at least at 12" of any Scout.The Spore Mine clusters enter the game as described further.

Objectives:

The Space Marines win if at least one of their figs leaves the table through the "Arrival" edge or if all the Gargoyles are killed.The Tyranids win if all the Scouts are killed.

Game Sequence:

1-Pursuit Phase
2-Movement Phase
3-Shooting Phase

+++ Pursuit Phase +++

This mini-game doesn't use the normal movement rules. The illusion of a high speed chase is recreated during the Pursuit Phase which determines all the events that may occur during such a chase. To achieve that, you must move everything on the table in the opposed direction from the arrival. The terrain pieces must always move back, but the figs may decide to maintain their speed, hence staying put on the table, or to slow down and move back too.Figs and terrain are moved in a precise order, starting by the furthest from the arrival edge and then the next until the closest from the arrival edge was moved. If there is a doubt on which object should be moved next, throw a dice.

When a terrain piece must be moved, move it of 12" away from the arrival. If the piece reaches the table edge opposed to the arrival, it is "recycled" and placed in contact with the arrival edge. The players take turns placing the recycled pieces, starting with the Tyranid player. The recycled pieces must be put at least at 2" of any fig or other terrain piece --if it can't then it is kept aside for the turn to be the first to be recycled on the next Pursuit Phase.

Each turn, one Spore Mine cluster can enter the game by being put in base contact with a recycled element. Spore Mines do not move during the Movement Phase, but are moved back along with the terrain piece they are "attached" to during the Pursuit Phase.

When a fig must be moved, the player who controls it decides whether it keeps its pace or slows down. Since everything on the table moves 12" back, a fig which maintains its pace doesn't move (since it is supposed to have moved of 12" the other way). If the player wants his fig to slow down he must decide how much he wants it to slow down: a fig may slow down by 1d6", 2d6" or 3d6". If a fig's orientation differs from the table's of more than 45°, it can't keep its pace and thus must be moved back of 12" (note that it can't slow down and will always be moved back of 12").
If a fig moves back of 3d6" and gets a result which would make it enter a terrain piece which was already moved this turn, stop its movement as soon as it enters in base contact with the piece. There is no damage to be taken.

Any fig which would leave the table during the Pursuit Phase is considered to have given up the pursuit, it counts as killed.

+++ Movement Phase +++

During the Movement Phase, the figs may move and turn. Note that this takes place differently than what is written in the WH40k Rulebook. It is important to determine the orientation of the bikes and Gargoyles for this game. We'll consider that the fig faces the direction in which it moves. The movements are done in a precise order, starting with the fig which is the closest to the Arrival (throw a dice in case of doubt).

Each fig can move 6". For each 2" moved, it can turn of 45°. A fig must move of 2" before being allowed to turn -- you cannot move it 4" and then turn 90°, or first turn 45°, then move 6" and turn 45° again.

A fig may also accelerate and can be then moved 12", but in that case will only be allowed to turn 45° for each 4" moved. (See above rules for movement limitations.) Note that you are not forced to move a fig if you don't want to.

If a fig enters into base contact with a friendly fig during any of the phases, its movement is immediately stopped.

If a fig enters into base contact with an enemy fig, it must immediately stop its movement and the enemy cannot move during that phase. A combat must be resolved immediately using the usual CC rules from the WH40k Rulebook. The fig which moved to enter in contact with the other counts as charging for that round of CC, unless it did so while slowing during a Pursuit Phase. If the combatants are still in base contact after the combat (i.e. if one of the sides isn't killed by the other) then all the involved figs will be left in place during the next Pursuit Phase and another round of CC must be made, they are considered to be fighting while moving alongside each other at normal speed --resolve any contact with Difficult or Impassable terrain normally. If they are both still alive by the end of the Pursuit Phase, they will be allowed to break contact (without any penalty) during the next Movement Phase, a dice roll decides who gets to move his fig first. If they nevertheless remain in contact then another round of CC must be made, etc...Note that this means there can be 2 rounds of CC per game turn.

Difficult and Impassable Terrain

If, during a Movement Phase, a fig enters a Difficult terrain, continue to move it normally, for each 2" (complete or not) moved within the terrain, the fig must succeed a dangerous terrain test or suffer a Strength 5 hit without Save. Note that Gargoyles fly over size 1 terrain without problem. If the fig fails the test but survives it will be considered "stopped" on the next turn and will be moved along with the terrain piece during the Pursuit Phase. It will also have to succeed another dangerous terrain test to be allowed to move during the Movement Phase (a failure doesn't imply a hit though). Three such test can be taken during a single Movement Phase, but for each test failed the movement is reduced by 2" (i.e. first test succeeds=>move 6", 1 failed test=> move 4", 2 failed tests=>move 2", 3 failed test=> stay put and wait for the next movement phase...)

If a fig collides with Impassable terrain or with one of the table's long edges it suffers a Strength 5 hit without Save. If the fig survives, it stays in contact with the piece/edge and can be oriented in any manner by its player. If such an incident happens during the Pursuit Phase, continue to move the piece of terrain normally, the fig moving back with it.

If any fig (even the Gargoyles) enters in contact with, or shoots within 2" of a Spore Mines cluster, it explodes -- see the Spore Mines rules in Codex Tyranids. Note that there cannot be more than 4 clusters on the table at any time but that clusters may be "recycled" after having exploded.

Note that the Fleet of Foot and Turbo-Booster rules are not effective during that mini-game...

+++ Shooting Phase +++

During that phase any fig which did not accelerate (i.e. moved 12") during the Movement Phase can shoot at any enemy within range and within a 90° arc in front of it. If the Scout Sergeant is equipped with an additional shooting weapon, and if he did not accelerate during that Movement Phase, he can shoot with that weapon at any fig within range, even if it is out of the front 90° arc, but, in that case, his CT is reduced to 3 (to account for the fact that he's trying to shoot "over his shoulder").

The shooting is done in a precise order, starting with the fig which is the closest to the Arrival, in case of doubt the fig with the highest Initiative gets to shoot first.

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This mini-game was great fun to play during the campaign, so much in fact that we've replayed it as a "stand alone" quite a few times since then.

It is also easily adaptable to almost any army you may want to play it with. In most cases, you simply have to pick a likely Fast Attack choice in each of the armies and start playing! For example, if you play with Imperial Guard and Tau then pick a squadron of Rough Riders and Gun Drones, the spore-mines become "simple mines"...
Of course several configurations may require a bit more of thought and modifications, but it remains relatively easy.

If you see a way to get rid of the "sizes" to really upgrade this mini-game to 5th ed and yet keep the gestion of the different terrain pieces quick and easy (to keep a fast pace in the game resolution, which helps with the "high-speed chase" feel), I'm all ears!

Welcome to the Vaults of Mars...

Being a Warhammer 40000 player for almost two decades now, I've always favored the fluffy* approach over the competitive one. I must admit I rarely, if ever, attend any tournament.
In fact, I mostly play with a small group of friends who, like me, prefer to play in campaigns rather than stand-alone games. Well, I also do a lot of playtest games, since for the campaigns I keep creating new units, scenarii and/or Codices...

Those friends say I usually create balanced, funny and fluffy rules. But they don't realize how much work it requires. And here's the reason for this blog: I thought it was time for me to share some of those creations and not let all this work go to waste.

All the house rules, scenarii and new units I intend to post here will be of one of two types: either of the "WiP" type, in which case I hope your feedback will help me to make them better; or of the already playtested kind, in which case I hope you'll find a use for them in your game.

Well, that'll be all for today, see you soon for the first real entry! ;)

/Nash

[* - If you want to take a peek at (some of) the fluff I've written, you can take a look at my other blog "Chroniques du Secteur Avéroïn" (http://averoin-sector.blogspot.com/)... Being able to read French is mandatory though ;) ]