Aug 272007

Originally posted at The Forge

David Artman


Hit Location Matrix

Hit Location Matrix by Christian (xenopulse)

If you want to be random, roll a D20 and a D12 and find the cross-section. That’s where you hit. And yes, it means you can miss if you roll outside the human bounds. (You can add weapons or shoulder bits or whatnot, too.)

Now, if your skill is great or your roll good, you just select a sub-section of the matrix to determine where you hit. So if you’re a crackshot, you could pick a 6×6 area out of the 20×12 area, say “first D6 is 4-9 on the x-axis, second D6 is 7-12 on the y-axis.” Or, in short gamer lingo, “6X4, 6Y7.”

That’s a VERY cool idea for an aimed shot, and it might even work with melee and my ideas about ebb and flow, too.

  • A melee attack skill lets you pick the quadrant you’re aiming for and determines the “area” of it. Different skills and/or weapons allow for larger or differently shaped areas.
  • THEN, you can delay to narrow down that area further (aiming/calling a shot). Of course, if you delay enough that the defender’s “initiative” comes up, he might attack ahead of you.
  • The KEY is that, once you’ve rolled to hit a quadrant, your weapon is in that “area” until some later count of initiative. This positioning, in turn, adjusts your chance of parrying against attacks against you in that quadrant.
  • SO if your opponent then gets to his initiative count and attacks in that quadrant, you’ll have a bonus to parry. Conversely, if he attacks elsewhere, you have a penalty as you try to haul your weapon into that new quadrant… should you choose to do so!
  • REPEAT. Now HIS weapon is in some quadrant for some time period, and that impacts HIS defensive capabilities.

Sprinkle liberally with hindering effects from limb hits, bleeding out from wounds that aren’t instantly lethal, and attacks to subdue; and I think you’d have a nice system with high verisimilitude but minimal handling. Basically, every combatant would have a chart (like that cool grid above) and maybe some tokens or a dry erase marker (laminate the grids) to mark their weapon’s current quadrant and which of their quadrants was last attacked (i.e. their opponent’s weapon position).

Hmmm…. Wonder if you even need a randomizer, then, or if it could all be done with resource allocation (like action point systems). Ooo! And in such a system, delaying or aiming is how one gets more resources! Spending them dictates how accurate the hit was: you only miss because your opponent expends more resources defending (to “push” your hit off his body grid) than you spent attacking (to “pull” your hit to the best spot in the quadrant that you want to hit).

OK, that’s the general notion; here’s the more formal structure of it:


Ebb & Flow uses this chart of valid hit locations and a concept of Action Points (APs) that determine, without randomizers, an attack’s success and effects on the victim:

Improved Hit Location Matrix

That chart shows the hit locations (red rectangles) for each significant body part. The more boxes there are in a location, the easier it generally is to hit that location. Yellow locations, when hit, generally prove lethal; green locations prove lethal over time if not treated OR have other systemic effects like being disarmed or tripped (system TBD).

Combat Begins

Most often, combat begins when a character makes its initial attack against another character. At that moment, all combatants’ Action Point Pools are refreshed, presuming that no long-term effects of damage have temporarily reduced them.

Action Point Pool

Determined by adding together the APs granted by each combat skill–some grant more than others, while some grant none but instead have other combat effects (disarming, tripping).


Ebb & Flow combat is not turn-based. Instead, every character has an Viscosity statistic, which is how many “ticks” of time pass after each attack attempt before the next attempt (or aiming) may occur. A tick is not equal to a second (more like a tenth of a second), and it is only intended to be a loose metric of time passing in-game.

Heavier weapons, generally, increase a character’s Viscosity but also increase or meaningfully change the “attack profile” (below).

Initial Attack

An initial attack may be declared by a player at any time: to start a combat or in response to being attacked (if the attack is dodged, but not if it is parried).

The attacker simply states the number of APs that he or she is investing, what type of attack (i.e. what “attack profile” per below) and, therefore, which squares he or she is targeting with those points. Those three pieces of information determine the direction and ferocity of the attack.
(Ex: 6 AP sword attack–swords provide an additional target square per 3 APs–to target squares D4 to F4: an attempt to lop off the victim’s head!)

Attack Profile

Basically, most weapon types have an AP cost to add additional target squares to an attack. This changes the “profile” of the attack, when an attacker opts to take advantage of it. Some weapon types (usually huge ones) even grant some initial, extra target squares for free, usually with a much higher increase to Viscosity than lighter weapons.

Linear – The attack profile weapon must “extend” additional target squares along a single line of contiguous squares.
(Ex: Zweihander: 2 free target squares + 2 AP per additional target square (linear profile); +10 to Viscosity; 5 APs to draw, starts at C1)

Square – The attack profile must designate additional target squares to make the overall profile as square as possible, which makes using weapon parry much more costly in terms of APs (i.e. each “row” of target squares must be pushed off a hit location; they do not push off en masse).
(ex: Maul: 1 free target square + 2 AP per additional target square (square profile); +15 Viscosity; 8 APs to draw, starts at A/I15)

Scatter – The attack profile may designate additional target squares anywhere on the hit location grid; e.g. a shotgun blast or multi-headed flail, which makes both parry and dodge more costly in terms of APs (i.e. the defender will have to pay big to “connect the dots” with a swirling, sweeping parry, to gather them all up and shove them off locations; OR he or she will pay heavily to individually move each one off all locations [i]in the same direction[/i] (i.e. dodging a huge distance in the opposite direction).

[And then there would be a laundry list of weapons]


The defender may then respond with the number of APs that he or she is investing in defense.

Dodging – For each point invested in defense, the defender may move one of the target squares ONE square in a direction; if enough points are invested to move all target squares off of all red boxes, the attack will be a miss. Note, however, that ALL target squares must be moved in the same direction, to the same ending square (this is very important later)! Note that dodging implies movement of the defender’s stance (distance per square TBD) and, as such, might very well result in other effects based on terrain (system TBD).
(Ex: D4 costs 1 AP to move to C4, E4 takes 2 APs, and F4 takes 3, for a total of 6 APs to move the sword into C4: a deft dodge to the left)

Parrying – For each point invested in defense, the defender may move one of the target squares TWO squares in a direction, so long as his or her weapon target is also moved to a square adjacent to that ending square. Alternately, the defender may use APs to move his or her weapon target to a square adjacent to a target square and then move it [i]AND all other target squares in the line of movement[/i] ONE square per AP, and his or her weapon target remains in the square just “behind” that line of movement. His own weapon target, in turn, must also end off a red box: no parry may leave your weapon target on one of your opponent’s hit locations. Put differently: when parrying, your OWN weapon target can hit you, if not also moved off any red box!). Note that an unarmed defender may not parry a weapon attack, and a weapon parry of an unarmed attack is automatically a hand hit.
(Ex: Suppose the defender above had his or her weapon target at B3. He or she could, instead of dodging, move it to C4 (1 AP) then all the way “through his own neck” to G4 for 4 more APs, leaving the attacker’s weapon target in H4: a solid parry that leave him or her better off than the more expensive dodge above.)

Note that drawing a weapon costs a number of APs shown in the weapon description, and its target begins in the square designated by the description; and if it says “A/I” and a number, use the combatant’s handedness to decide whether it’s in the A (right) or I (left) column at the designated row.

Note also that this system utterly supports dual wielding: an attacker may choose which weapon target to move to attempt a hit, and a defender may choose which of his or her targets will be moved in a parry. Finally, a shield is, for all intents and purposes, a special kind of weapon that has a square-shaped target when parrying (2×2, 4×4, or even 6×6 depending upon size–thus, they can move “square” profiles en masse), a typically higher Viscosity increase to wield than a weapon, and a very high additional target square cost (i.e. one can only poke someone with its center spike or slash at the victim with its edge).

Attackers and defenders MUST note the square in which their weapon targets end up after a defense; it is relevant to follow-up attacks against the victim.

Follow-Up Attacks

Follow-up attacks work just like the defense system–in fact, Ebb & Flow is little more than investing effort to be the one who finally has the AP surplus and weapon target positioning to make a decisive blow.

Basically, if the character is not counting off Viscosity ticks, the he or she may spend APs to move his or her weapon target from its current square to a different square, one AP per square moved, and then may invest further APs to change the attack profile.

A defender invests APs to move the target square(s) with a dodge or parry, per above. Note that a defender might have to suffer effects of a lesser hit–for example, pushing a hit from the upper torso to an upper arm–if he or she does not have enough APs or doesn’t want to use them all up in defense.


At any time when a player is not counting off Viscosity after an attack attempt, a player may delay (i.e. not attack) for one tick to receive one AP to his or her AP Pool. (Or maybe this is something that varies based on a combat skill or skills, instead one-for-one.)

I think that’s sufficient to illustrate, maybe even to test.

OK, so what’s missing, here? Where’s the obvious min-max uber strategy? Where’s the first-turn kill? (Assume whatever in AP Pools, so long as they are fairly close between defender and attacker–this system does NOT give a significantly weaker defender much of a chance to survive; there’s not “lucky blows” here, other than (maybe) combat skills that tweak AP costs let you jump ahead in Viscosity count….)