Although I will point out, the moment you make suppressive fire good enough to be effective against multiple enemies, you then risk having suppression fire being used all the time, why use single shot or double tap, or even spread burst, if you can potentially kill 3-5 or so with one action, and decent chances of doing so, or at least cripple them. You could end up ruining the game, isn't that the most important thing to consider
That is a very valid point.
My carefully considered answer is...
Shouldn't it be used all the time? After all, that's basically how real firefights work. PCs with automatic weapons and suppressive fire skill (which is by no means all of them)
ought to be using it first thing in combat. If the enemy don't take cover, they should get shot up, if they do take cover it reduces their percentage activity... It ought to be standard tactic, really, especially for a group which a military unit, even.
(In fact, with the benefit of hindsight, if it was a regular feature in combat, it might have gone a long way to solve the problems I had with SM:P activity system (and why I now use one based on RMC); in that, with snap, normal and long actions, the PCs could sometimes get three (or six if they used twin pistols) shots off a round... But if they were all and claiming cover (so capped at 75% activity), it would have made that problem basically nonexistant...)
Not everyone will (or can afford to) develop the skill, of course, so there's that as well.
Okay - let's try this then. Taking from the suppressive fire skill and the cover rules (BL pg21, here codified as Dive for Cover):
Suppressive FireSuppressive Fire is a Static Manoeuvre, rolled on the Suppressive Fire table (Blaster Law pg20). The Suppressive Fire skill bonus also determines the percentage of the user's weapon OB used to resolve attacks made during a Suppressive Fire action.
A Suppressive Fire action takes 50-100% activity (with any activity less than 100% imposing a penalty equal to the percentage less).
The firer picks an area to suppress, which wityh a burst weapon can be from a 1m radius around a single target to no more than an area of 5m by 5m by 5m. A continuous fire weapon can instead suppress a 10m by 5m by 5m area at no additional penalty, but is then resolved as a burst for the purposes of the manoeuvre roll and OB modifier.
A character can attempt to suppress a larger area than this, but takes a proportional penalty of -100 to the maneuver roll for each additional 5x5x5m area. (I.e. a character suppressing a 10x5x5m area would do so at -100, a 7.5x5x5m at -50).
A Suppressive Fire action suffers half the normal weapon range modifier to the manoeuvre roll (measured from the further point of the area). For every shot above minimum (5 for burst, 10 for continuous), add +1 to manoeuvre. The firer can only suppress a maximum of 1 target for every 2 bullets/shots fired (starting with the closest character, friend or foe).
The results of the static maneuver give an OB modifier on the table below (adapted from BL pg20).
-26 or less: Spectacular Failure (Burst -40, Continuous -25)
-25-04: Absolute Failure (Burst -25, Continuous -15)
05-75: Failure (Burst -10, Continuous -5)
76-90: Partial Success (Burst +0, Continuous +5)
91-110: Near Success (Burst +10, Continuous +15)
111-175: Success (Burst +20, Continuous +35)
176+: Absolute Success (Burst +30, Continuous +45)
Resolving Suppressive or Area AttacksAll affected characters in the area of a Suppressive Fire attack or with the radius of an area-effect attack (eg grenade,
Fireballetc) have three options.
1) Characters can ignore the Suppressive Fire/ explosive attack and risk being hit.
The attacker resolves the attack as a normal weapon attack, using as the OB their Suppressive Fire skill bonus as a percentage of their weapon OB, plus the static manoeuvre OB modifier. (This net bonus cannot exceed the character's normal weapon OB.) Explosive attacks are resolved using double their (net) blast attack bonus. Explosives further have a blast radius modifier of -50 at Short Range and -100 at Medium Range.
The defender only counts DB from static sources, i.e. active shields and armour quality (or appropriate magic). They gain no DB from cover, Quickness, ranged parry or Adrenal Defence (etc).
2) A character already in cover may claim the cover bonus. They lose 25% activity next round, but retain normal activity this round.
The attacker resolves the attack as a normal weapon attack, using as the OB half their Suppressive Fire skill as a percentage of their OB, plus the static manoeuvre OB modifier. (This net bonus cannot exceed the character's normal weapon OB.) Explosive attacks are resolved using their full blast attack bonus. Explosives further have a blast radius modifier of -50 at Short Range and -100 at Medium Range.
The defender gains their normal DB, plus double the cover DB bonus.
3) Character not in cover can attempt to drop prone or make a Dive for Cover action (see below). In both cases, the character loses all remaining activity this round and 50% next round.
The attacker resolves the attack as a normal weapon attack, using as the OB the static manoeuvre OB modifier only. Explosive attacks are resolved using their full blast attack bonus. Explosives further have a blast radius modifier of -50 at Short Range and -100 at Medium Range.
The defender gains their normal DB, plus double the cover DB bonus. Characters that drop prone gain a +15 DB for being prone
1, but gain no cover bonus (unless there is cover for the to fall into, in which case they get the benefit from the cover as well).
Dive for Cover: The character must have appropriate cover within a distance equal to half their Base Move Rate. The character makes a manoeuvre roll. The base difficulty is Light (+10), increased by two levels (Hard (-10)) as a reaction to normal weapons fire, or by four levels (Extremely Hard (-30)) as reaction to an area-effect attack (e.g. grenade) or Suppressive Fire. A character may attempt to reach cover further away than half the BMR by moving at a faster pace, but this increases the difficulty of the manoeuvre by one level of severity per pace increase (e.g. one for jog, five for Dash).
If the character receives any result that is not a failure, the character receives that percentage of the cover DB bonus against that attack (and is then treated as being in that cover as normal.)
As a reaction, Dive for Cover uses up all the character's remaining activity this round and uses 50% activity from the following round.
Does that sound reasonable? Striking a bit better balance between making it not more powerful than regular fire, but not ineffective? (The cap at 100% weapon OB seems reasonable, and there's still some reason to develop Suppressive fire skill above 100 for countering other penalties etc etc.)
You might argue the penalties imposed for a poor maneuvre check could stand to be harsher (as it is, I coped them from Blaster Law) - or you could say that you only get to add your OB is you get a result above failure... Or it could just be left as it is.
(On the explosives, I recently - upon reading up on how grenades actually work - set all grenades/explosive to have basically three blast radius - the initial blast radius (which is the "lethal radius" in military explosive parlance) a short and medium range (the latter of which is the theoretical "wounding range;" good enough approximation for an RPF, I think.)
1You'd have thought somewhere in RM2/SM2/RMC/SM:P there would be a positional bonus for being prone, but apparently not. The closest there is is the +20 for a downed foe, but I think that really only should apply to melee attacks. So a +15DB for being prone should be a standard thing, I think.