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Revisiting Movement

Killing a few birds with one mechanical stone

Last night, I watched a History Channel show about battles in the Old Testament. Most of it was your usual "Billobab smote Jehosameme," and "Lo, did many chariots rumble." Amid all the smiting, inspiration struck.

During one of the Philistine invasions of the Jezreel Valley, it was noted that the Israelites wore leather armour while the Philistines wore heavier scale, which hampered their mobility in the mud of one particular battlefield. Saul and Friends won the day.

So I'm thinking, "How would I recreate that in Chimera?" And the answer smote me.

Dead Bird 1: Attack TNs

In the example above, terrain was a factor, but more importantly, it's a precedent for how a lack of mobility makes for an easier target. For whatever reason, the slower you are, the easier you are to hit.

Since shifting the Target Number model in Chimera a few weeks ago, I've wrestled a bit with the TN requirements for a successful hit. My original logic was to base it on defender size, such that bigger targets were easier to hit. But that doesn't quite sit well with me—for the average character, it made hitting goblins really hard and hitting giants or dragons really easy. While armour still absorbed damage, tipping the hit probability scales this way didn't feel right.

bible armour

Israelite attacking in leather armour

Thanks to the Philistines, I think the answer is: attack TN equals the defender's current Movement Rate (MR).

The fact that it's hard to hit fast things seems to be minimised in a lot of RPGs. Concomitantly, a combatant's speed rarely seems to be a factor during a fight (outside of how many squares on the battlemat each mini can cover).

Here's how it works: Billobab has MR 12". That means an attacker hits on a d20 roll of 12 or more. Now let's say Billobab wear mail and is laden with stuff so that his Encumbrance is 3, making his movement 9". Now an attacker needs a 9 or more on the d20. In other words, encumbrance not only affects your movement rate, but how easily you're hit.

Note that armour is still "ablative" in the sense that it absorbs damage. But with this change, lightly armoured targets are harder to hit, though they take more damage when they are. Conversely, it becomes easier to hit heavily armoured opponents, but damage will be lower. Parry and cover are unchanged (i.e., they add to the attack TN but have no effect on damage taken).

Dead Bird 2: Size and Movement

The only problem with using MR as an attack TN is that in Chimera, base movement is a function of creature size, so that the bigger a creature is, the higher its Movement Rate. My design logic (since version 1.x) is that big creatures take bigger steps and therefore cover more ground per round. This means that for big beasties with high MRs, you'd have crazy high attack TNs.

But I gotta admit: I've never completely embraced the bigger-equals-faster generalisation. A big, fat dinosaur might just lumber along, while a little, bitty housecat is pretty quick on its feet. However, I can easily rationalise separating the two: First, combat movement is more of a tactical thing, so in a fight, big fat dinosaurs cover just as much ground each round as a human-sized opponent. I mean, Cloverfield Beast was HUGE, and the little army dudes ran circles around him. Second, I don't recall a correlation between size and movement rate in pretty much any other RPG (cf. D&D B/X, where each character or beast—regardless of size—has one of essentially 5 or 6 movement rates: 30', 60', 90', 120', 150', or 180').

By "normalising" movement rates and decoupling from creature size, it doesn't seem like I'm breaking any major expectations or well-established conventions. Put another way, I can adjust movement to suit my other needs.

Dead Bird 3: Movement Rates

And while we're on the subject of movement, let's discuss crawling and running. In Chimera, MR represents walking—how many 10' blocks you can cover at walking speed. Crawling or creeping is half one's current Movement Rate while running is double. Easy enough, but if I'm using MR to indicate attack TN, then characters will be come invulnerable simply by running around (i.e., if Billobab has MR 9", I need an 18 to hit him while he's running).

So part of this exercise is figuring out how to make movement realistic without making combat too hard (or too easy). As I recall, Savage Worlds uses a die roll to indicate running speed, which is an interesting possibility. So how about this:

When you creep around, you still move at half your MR. But when you run, you roll a die and add the result to your MR—the result is how much you can run that round. This lets you reflect fast creatures (or beasts what can sprint) without giving them ridiculously high Movement Rates—just give them higher running dice than normal. For example, a human might get 1d6, while a horse gets 1d10.

Putting It Together

Let's say a human's base MR is 12"+1d6. This means that, unencumbered, he moves 12" per round. He can creep or crawl at 6" per round. When running, he adds 1d6 to 12 each round (i.e., he runs between 13" and 18" per round). Let's also say a goblin's MR is 12"+1d4—he crawls at 6" per round and runs between 13" and 16" per round.

The human is wearing mail (Enc 2; DF +2), carrying a shield (Enc 1, Parry +1), a broad sword (Enc 1) and gear (Enc 1). His total Encumbrance is 5, reducing his actual MR to 7"+1d6. Now he crawls at 3", walks at 7", and runs between 8" and 13". When attacked; these values represent the Target Numbers required to hit him, depending on what movement mode he's using (hint: don't get caught crawling). However, because he has a shield, attack TNs are increased by +1. If he is hit, his mail reduces damage by 2.

The goblin is wearing leather (Enc 1, DF +1) and carrying a short sword (Enc 0). His total Encumbrance is 1, reducing his MR to 11"+1d4. You can do the math to figure out different movement modes, but it's easy to see that his lack of encumbrance makes him harder to hit during a fight, but not at the expense of an outlandish MR, tons of armour, or size-based assignments. Plus, when he is hit, his lighter armour will let more damage through.

Final Words

OK, that's a lot to digest—pretty much a late-afternoon mind dump of a thought I've had for only 16 hours and no doubt has holes.

But I think this has serious merit, and I'm going to test it out. Thoughts appreciated—have at it.

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  1. deimos3428
    March 31st, 2011 at 16:35 | #1

    1. I’m not sure I understand the point of the randomized running speeds. One more time for the kids at the back please, professor!

    2. Using the base MR as base TN is pure genius. Using the adjusted MR seems considerably less genius-ish. Unless there are other problems associated with just using base MR that I’ve missed.

  2. March 31st, 2011 at 17:14 | #2

    @deimos3428 : I’m not sure I understand the point of the randomized running speeds.

    If you merely double MR to reflect running, then you’ll end up with unobtainable attack TNs. I haven’t figured out the full range of movement, but I’m thinking it’ll go on a x4 scale: MR 4″, MR 8″, MR 12″, and MR 16″ (there will probably be outliers above 16 and below 4, but these are probably the “mainstays”). In this case, a running MR 16″ dude would be hit on TN 32.

    The randomised value is a compromise–more than walking, less than double. Also, since I have fewer MRs to assign, I need a way to reflect “degrees of fast;” dice seem a good starting place: A human and a horse both walk at MR 12″, but the horse might have running dice of 1d10 while the human just gets 1d6. Finally, I like the randomness of it.

    Note this isn’t an issue if you always use the target’s base MR as the attack TN (i.e., don’t adjust for crawling or running).

    [Side note: I always hated “running” as a skill or non-weapon proficiency. I say anyone can run, but it’s always endurance–the question is how far…using dice addresses this for me.]

    Using the adjusted MR seems considerably less genius-ish.

    I’ve always wanted to simulate the difficulty of hitting a moving target, but without assigning what amounts to a static modifier (i.e., if the target is moving, attack at -2; if the target is moving at greater than MR X”, attack at -4…).

    It’s a more tactical approach and may be a pain–playtesting will tell, but I like how it looks on paper.

  3. deimos3428
    April 1st, 2011 at 12:18 | #3

    Ok, I think I get it. I have a couple more thoughts to make your head spin, mostly off the cuff:

    I erred up there slightly when I said “base TN=base MR”. I meant to suggesst “base TN=MR adjusted for encumbrance/environment”. So I’m suggesting that carrying heavy stuff would apply, as would slogging through mud/snow or being magically made faster/slower for that matter.

    But I don’t think whether you’re crawling/swimming/flying/running/walking/skiing, even though it affects your MR, should apply to TN. I’d just keep the simplicity of the 2x factor, but not have it adjust TN.

    The reason being, there’s a difference between being nimble (adjusted base MR) and being fast or slow (adjusted base MR x2 or x 0.5 or +1d6), and I don’t agree that the latter particularly affects defense.

    Some examples I’ve thought of, and additional ponderings:

    1. Consider a target actively running away from or towards a missle fight.

    Excepting range and facing, which would be straight TN modifiers, there isn’t much difference in defense. If they’re moving directly across the field of attack, there might be some adjustment to TN for a moving vs. stationary target. But I don’t think the speed difference is significant enough to warrant a doubling/halving of TN or even a largish random die increase.

    2. Consider a target actively running away from a melee fight (towards or across being somewhat irrelevant).

    Generally speaking the actual speed of the target won’t matter, as they’ll be out of melee range on their turn, either before or after the first attack. This assumes the attacker is standing still, and attacking.

    3. Now how about something more dynamic? Assuming your MR 7 character is being actively chased by a marauding MR 12 creature (perhaps a tiger). The tiger need spend only 7 MR to keep in melee range; he can’t be outpaced. There’s no reason he couldn’t claw you and chase you run away. Perhaps a -5 to TN to cover the MR delta applies?

    That might be a bit more detailed than you’re going for, but make of it what you will.

  4. April 3rd, 2011 at 10:19 | #4

    @deimos3428 : You’ve convinced me–good point distinguishing fast from nimble. Though I still like the random running die. So here goes:

    1. Attack TN = adjusted MR (i.e., MR modified by Encumbrance and terrain)

    2. Crawling: half adjusted MR (use while Sneaking or crouching; the latter is a Core Rules thing)

    3. Running: adjusted MR + some die to reflect speed

    Bonus: because Wound Penalty applies to MR, it’s now easier to hit a wounded target. Same with Fatigue.

    I need more info on your point #3. I think I see where you’re going, but another example would help. Please include a Kaiserbot (MR 8″+1d4).

  5. deimos3428
    April 3rd, 2011 at 17:58 | #5

    Ok, will try to expand that last thought. I think I actually got it a bit wrong last time, so this will be slightly refined yet again.

    A Kaiserbot is chasing down your heavily encumbered character (MR 7″ + 1″). As it is running, it moves at 12″ (MR 8″ + 4″; Kaiserbots are renowned at rolling well). The character’s base TN is 8. That sounds pretty grim, as it has a MR 4″ advantage on your character, and would attack at -4 TN, or 4.

    But I forgot…there’s also the attack-half-move-half convention to consider. In order to attack at all, it’s going to need to slow to MR 6″…move half, attack half. So you’ll start to pull away, but as long as while you’re still in flailing hooks range, it’ll get an attack at +1TN (TN 9) every round (it has two hooks, presumably). Plus bonuses for attacking from behind, if any.

    Of course, you’re both slower than the tiger on average at MR 15-16″, now…so you only need to outrun the Kaiserbot.

  6. Kenkins
    April 4th, 2011 at 20:39 | #6

    Would someone caught surprised while sneaking (or other application of half MR) use the slower MR as the base attack target, then return to full MR on the next turn?

    I’m likewise interested to see an answer to the “what if I had to move to attack you?” question. I was drawn to this system by its overall elegance (and via Stargazer’s World), and love watching the design unfold with that in mind at every step.

  7. April 4th, 2011 at 22:01 | #7

    @Kenkins : Hmmm…I think someone caught Sneaking would be attacked at half MR only if the Sneak was a Critical Failure. That’s something I probably wouldn’t make “official” in Basic, but might suggest in the Core (wherein Abilities are more fully described in terms of Action Roll results).

    I’m still chewing on Deimos’ refinement above. In his example, the Kaiserbot has a 4″ advantage over the character, but it achieved it by running, which is a full action. An attack on the same round suffers the multiple action penalty of -2.

    This example suggests that the character won initiative and chose to run 8″. The Kaiserbot’s response was to run also–I’d rule that he catches up with the character after 7″ (to put him in 1″ melee range). He could have done this by walking his normal MR 8″, but since he ran (full action) his attack roll has to be a 9 (base TN 7, plus -2 penalty). The details of slowing down and pulling away could be described by the GM, but I don’t think they need to be represented mechanically (?).

    The attack-half-move convention is somewhat built in if you’re doing it at your normal MR. IOW, the character can move up to 7″ (walking is a free action) and still attack without penalty.

  8. scott
    May 19th, 2011 at 11:07 | #8

    Im all about the move rate for tn. makes combat seem more hectic, if you dont want hit, then move. However, i think i am going give a modifier to the ar based on size difference. so if a human (medium size) is fighting a housecat (tiny size), the cat would gain a +4 since the human is 2 size categories larger while the human would get a -4. I will experiment with this but i thought i would see what your thoughts were.

  9. May 19th, 2011 at 19:30 | #9

    @scott : I’m interested in seeing how this works for you. We playtested with a couple of size-based AR mods, and while the results made sense, it was just a hair too much bookkeeping for my style. But I like the concept and if it works for your group, let us know!

  10. scott
    May 23rd, 2011 at 10:11 | #10

    @Erin D. Smale
    Im also looking at creating starships based on the basic monster stats. once i type it up, could you look at it? i am adding the consept of hardpoints to customise the ship with weapons of other usable space.

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