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Thursday, September 25, 2014

Percentile Dice and the Psychology of Sucess

10-sided dice
What are the implications of percentile dice for game design?

Percentile dice were really popular in the 80s and early 90s.  Call of Cthulhu, Palladium Games, and many others used percentile dice for their skill systems.  More recently, the Warhammer games have been revamped, including their percentile-based resolution, in Dark Heresy, Rogue Trader, and so forth.

The main advantage of percentile dice derives from their transparency.  We are used to calculating odds in percentages anyway, so when a player intuitively understands them.  I may not know in my head how likely I am to roll over thirteen on 3D6, but I do know what 20% or 57% means.

The disadvantages of percentile dice are more subtle:  it is very difficult to design a system that uses them, in which there is an interesting variety of rolls and modifiers, AND in which player results will occupy a desirable central range of probability.

Other common types of die rolls (for example, 3D6) result in a curve.  The central numbers of the range are more likely to occur than numbers near the edge.  On a 3D6, not only is the average (mean) roll likely to be 10, but 10 is also the most common result (mode).  The graph of a percentile roll is flat, not curved.  You are just as likely to roll a 02 as a 50 or a 98 or any other number.  This is part of its nature. 

As a game designer, I find a dice that produce a bell curve much more useful than dice whose results are flat.  From the perspective of interesting game play, I want players to be rolling results that range from fairly likely to fairly unlikely, say from around 40% to around 80%, most of the time.  Basically, players are most engaged when they have a pretty good change of succeeding, without it being a certainty.

For example, in a rolep-laying combat system, the round usually goes around the table.  In my typical group, I get to take an action about every 10 minutes of game play.  I want it to be good one.  (I want to hit the monster.)  But I want the thrill of knowing I might fail.  Always hitting it, or never hitting it, or nearly enough, is just boring.

A curved dice result naturally fits these criteria, with the dice themselves pulling the result towards the middle of the range, while allowing the diminished possibility of extreme success or failure.  Percentile dice do not.

Now, a game designer could create a similar situation using percentile dice: just make sure the modified odds are between 40% and 80%, or whatever is the desired target range.  But here we run into the second problem -- differentiation. 

Players also like to have meaningful differences in their rolls and in the game statistics used to represent them.  They like to have characters with strong skills, weak skills, and medium skills.  In a wargame we want to have super tanks, mediocre tanks, and shitty tanks.  We also (usually) want to have modifiers, for easier or harder situations. 

Here again, I find a curved result more useful in design than a flat one.  3D6 - 3 or 3D6 +5 will have higher and lower average (mean) results, with the mode shifted to one side or another.  Large modifiers to flat percentage rolls will quickly knock the (mean) result out of the sweet spot altogether.  The target number is usually too low, or too high, or appropriate differentiation is just boringly small.  ("Oh, boy, my Firearms skill went from 66% to 68%! I'm the MAN!") *

So, that's why I don't like percentile based skill or combat systems.  Sorry, Call of Cthulhu, you are one of the great games of all time, but your skill system is terrible.

What, then, are percentile dice good for? 

I don't like them as a core mechanic, but I do like them for being able to set rough odds, and then immediately test them.  ("How likely is it for that Ogre to be at home when the players arrive at the cave.  It's dusk, so... 40% chance?  Roll it.")  Other than that, they are not my favorite instrument.

(In case you're wondering, I don't have the same problems with a D20 as I do with a D100.  A D20 is more roughly granular than a D100, having a smaller range of results, and, if you are adding whole numbers to it, modifiers seem psychologically significant while not breaking the scale easily.)

Monday, September 8, 2014

The Open Hand (Part I)


All arts have length and measure.

-- Johannes Liechtenauer

I'm considering how to make a melee combat system for roleplaying games that better simulates historical fencing.


For a few years, I've had a casual interest in the late medieval/renaissance fechtbucher and schools of combat.  These manuals describe the techniques used in civilian combat and duels: typically unarmored, with a one or two-handed sword, buckler or dagger.  Later books in the same genre describe fighting with early rapiers, again paired with an open hand or a secondary weapon.  Various modern teachers and organizations have reconstructed these techniques for sport and practice.   (If you're in Richmond, Salle Green offers a variety of courses.)

I have found the experience to be very different from the manner in which most roleplaying games depict these weapons and the experience of using them.

In games such as Dungeons and Dragons, or online games such as the Elder Scrolls, the various combatants are represented as having a measure of health.  Weapons are represented as having a range of damage.  The fighters proceed to whack at each other.  If hits are successful, "damage" is subtracted from "health" until one combatant is dead.  Winning a bout usually takes multiple blows on a foe, and no one seems to take significant impairing injury until they fall over dead.  Overall, the effect is like seeing two mounds of spam whittle away at each other with cheese graters.

Instead, I'd like to offer the following basic assumptions for a combat system:
  • Any weapon, with a proper strike, is potentially deadly. I'm tired of seeing roleplaying games in which weapons are rated entirely based on how big they are when clobbering someone.  Knives (typically the most pathetic weapon in an fantasy roleplaying game) are a dangerous weapon in real life.  Doubt me?  (https://www.youtube.com/watch?v=uDGHKyB3T_U)
  • A single, well-executed strike can potentially kill or incapacitate any opponent. Whether you are Andr'e the Giant or Steve Buschimi, a rapier-strike in the torso is deadly.  No matter how big and tough a person your may be, your liver is not especially better at repelling 6 inches of steel.So big tough strong characters should better resist minor injuries, but not so much lethal strikes.
  • The combat is a contest of skill (and luck),  positioning and reaction. Fencing is about timing and distance, attack and parry, and the geometry of the interaction of blades. 

Furthermore, I'd like my system to incorporate some general observations on Renaissance weaponry and the interactions between main-hand weapons and use of the off-hand, either open or with a dagger or buckler.

  • In most combat systems, a one-handed sword forms the basic teaching weapon.  In medieval systems, this was an arming sword which could either cut or thrust.  As we move into rapier combat, it becomes more and more a thrusting weapon, with an increasingly vestigial cutting capacity.  Much of the footwork remains similar, and less rigidly linear than modern fencing, as fencing would be in the round rather than on a piste.
Rapier. 17th century.  Wikipedia.

  • The off-hand was always an important element of combat, regardless of whether it was holding anything, and indeed, open or equipped it was put to similar uses.  Even an open hand can push a blade aside, grapple an opponent, or deliver a punch. Indeed, some techniques involve dropping a weapon at close range in order to better grapple. Many things were held in the off hand: daggers, bucklers, secondary swords, even lanterns or capes.  But their roles were all fundamentally similar. 
  • Grappling and throws.  Wikipedia

  • Most roleplaying games assume that the purpose of a secondary weapon is to make a second attack, and fighters with a sword and dagger are portrayed as super-chopping death-Cuisinarts (usually with a decreased chance of self defense). I' don't think this would be the case.  A fighter armed with a secondary dagger might stab with it, if he got in close, but he would be more likely to use the dagger to parry, and to control his foe in order to strike with his main weapon.  Indeed, the dagger's main use as a weapon (rather than a parry stick) would be inside the reach of a sword, in the same sort of way as a fighter with an empty hand might punch or grapple or strike with the pommel.
  • Sword and Buckler (late 13th century).  Wikipedia.
  • Likewise, most roleplaying games give a hefty defensive bonus to a shield.  This might be so with a large shield, but these were not often used in civilian combat of the period.  Instead, the more common implement would be a buckler, a shield about the size of large dinner-plate or a platter (for the big ones).  A buckler cannot protect one's entire side, but used actively it parries well.  Up close, it can be used to impede the opponent's blade movement, or you can punch them with it. 
    The two-handed longsword in different positions.  Wikipedia.
  • Two-handed swords(like a two-handed sword or a bastard sword) are fast, versatile weapons.  A typical Renaissance two-handed blade is about a foot longer than a one-handed sword, with maybe another half a foot more handle. The main hand holds the handle near the hilt and acts as a pivot, with the off-hand on the lower handle or pommel.  (Much like holding a baseball bat.)   This is one of the most satisfying of weapons to swing around, and it's one that I think most roleplaying games get completely wrong: most games give the weapon a bonus to damage, but lower defense or speed.  However, in my experience these swords are not especially heavy (only about 3 pounds max).  The may indeed strike with more force than a shorter weapon, but as I said above, I'm not sure how significant this would be, since even a smaller weapon is capable of a lethal blow.  Neither are two-handed swords slow or awkward -- they are quite capable of parrying, having an extra foot or 18" of steel with which to do so.   This compensates for not having a buckler or parrying dagger, and up close the pommel can deliver blows like the butt of a staff.  The greatest advantage of a two-handed sword is, in fact, one one that few rpgs address adequately -- range.  A two-handed sword can strike an opponent a pace or so farther away than a normal sword, meaning an opponent must enter its range before being able to make an attack of their own.  Incidentally, there is an even bigger two-handed sword, used to attack pike squares that's even bigger.  Such huge weapons are a bit awkward and might justify the rpg stereotype. 
Hitting someone in the face with the pommel of a 2-handed sword.  WIkipedia.

Next time: I will try my hand at modeling these assumptions in an rpg combat system.

Friday, August 29, 2014

Publishing Speed

Games Workshop released the Grey Knight Codex this week, only a month after the Space Wolf Codex and a Space Wolf supplement.  They are also pumping out the Sanctus Reach Campaign volumes.

These are all color hardback volumes, of a more or less standard size.

Overall, Games Workshop has been releasing books at an amazing rate for over a year now.  I'm assuming it is made possible by new digital publishing technologies. 

As readers will know, I think game companies should move to online rule and army books, but GW seems to be pursuing a vigorous strategy of many books, released frequently.  They are pretty expensive too, at 50$ each.

What does it mean for a game when even seriously devoted players cannot afford all the supplements, and thus cannot view the entire game environment?

Monday, August 18, 2014

Designing the Brutes

In Sabre and Raygun, the Brutes  desert nomads, gathered into varied tribes of different species and cultures.  The Brutes will be a horde army with weak shooting and strong melee.  I want players to build armies of Brutes from many different model ranges, with different sizes and designs of figures.  My test models have four arms and green skin, but this is by no means mandatory.

The Brute Force Book will introduce different Sizes of Brutes. The player will pick a Size category representing the majority species in their Force.  Their Core units will consist mostly of models of this Size. 

  • Small Brutes will be roughly human sized, and have no extra Toughness.
  • Brutes will be a bit larger than humans, and have Toughness 2. 
  • Large Brutes will be a lot larger than humans (think Ogre-sized) and have Toughness 3.

There may be other models mixed in here and there, representing other species in the tribe.  Support Units may be of any Size, representing allies.

The previous two force books featured Quality rankings for troops.  In the Colonies and Free Cities, units share a standard organization, but vary in their level of Skill and Leadership.  So Infantry or Cavalry may be untrained militia or elite veterans, based on the same list entry. 

The Brutes will use Quality differently than the Colonies or the Free Cities.  For the Brutes, Quality will largely be determined by the role troops play in the tribe.  Most tribes spend the majority of their time foraging or hunting.  They may have a retinue around their leader, but have no other standing army.  Most Brute combatants can be characterized as:

  • Unbloodied: The Unbloodied are young Brutes who have not yet tasted battle.  They will have Skill 1 and Leadership 4+.
  • Warrior:  Warriors are ordinary adult tribe members.  They will have Skill 2 and Leadership 3+.
  • Kinguard:  The Kinguard are a dedicated retinue of full-time fighters and nobles who accompany the leader and provide a core of leadership and striking power.  They will have Skill 3 and Leadership 3+.

Brute Units will typically have a fixed Quality rating, but a variable Size rating.  Most units will be rated as Warriors, and only a few will have the option of upgrading to Kinguard or downgrading to Unbloodied.

A typical Brute has a RoF 1/1/.5 rifle and a RoA of 3.  This means they are much deadlier in hand to hand than in shooting, and suffer little penalty for moving.  With a high average Leadership, they will be difficult to Suppress and will rally quickly.

As a Horde army, most Brute Units will be large, with a base size of 15 or 20 models, and the option to upgrade even larger, or to add Brutes of different sizes to the unit. 


Monday, August 4, 2014

Thinking about Horde Armies

Some Brutes
I'm currently working on the alien Brutes' Force Book for Sabre and Raygun.  So I'm thinking about that classic wargaming army type, the horde army, and how different games represent it on the table top.

A horde army is a big, stompy army with generally poor shooting and a massive payoff if you can bring it close to the enemy.  Horde armies feature lot of models, usually with sub-standard guns and an emphasis on hand to hand combat. A horde army tends to have lower-quality troops, either less skilled, or poorly equipped.  Not every army with lots of figures necessarily a horde -- massive shooting armies, like the Imperial Guard, Lizardman Skinks, or Saga Welsh have their own, distinct design issues.

In Warhammer 40k, the classic horde armies are Orks and Tyranids.  In historical wargames, the horde armies feature warbands of enthusiastic but poorly-disciplined fighters like the Celts or the early Germans. In Flames of War, the Soviets are often a horde army.

Horde armies challenge the game-designer to properly balance the risk vs reward inherent in the horde philosophy. 

Horde armies tend to be very good in hand to hand combat, but poor in shooting.  So in most games involving a horde army, the horde will be trying to close distance with the enemy.  The opposing force will be trying to shoot it down. If the horde is too resilient then it will always reach combat range in force, and slaughter the enemy.  If it is too flimsy, then it will never be able to close successfully, and will tend to loose.  So it needs to have just the right level of attrition and durability. Moreover, the horde needs to have some flexibility, some other factor than just running and charging, if it's not to quickly become boring. If you've ever tried to set up a D-Day beach landing scenario, you'll know that these are difficult balances to reach.

The film Zulu has inspired countless wargame scenarios of dudes with guns vs dudes with spears.
In point-based games, the cost per model of a horde's basic trooper will largely determine whether this balance succeeds or fails.  Hordes need to be big, so model prices should be cheap.  Horde armies also tend to take lots of casualties, and models that die before reaching combat are largely important only for setting a ratio of attrition.  

Many games therefore give a point break to their horde armies.  For example, in Flames of War, Soviet units are both bigger and cheaper than comparable units in other armies. Other factors, such as special rules, offset this cost reduction.  The Horus Heresy lists take a similar approach, encouraging maximally-sized units by having a relatively-high initial cost for the unit's minimum size, but giving a reduced price for further models.

Thursday, July 24, 2014

Thoughts on Malifaux

The game book.
My gaming group played a small game of Malifaux this week. 

Malifaux is a 28mm skirmish fantasy game with a Wild West theme.  Each side has around 6-8 models, on average.

Malifaux features some interesting game mechanics.

First of all, Malifaux does not use any dice.

Instead, it uses cards.  Whenever a player needs to generate a random number, they draw a card from their deck, which has Ace to 13 in each of four suites, and two Jokers.  The Black Joker is bad, and counts as a super-failure.  The Red Joker is good, and counts as a super-success.  Each numbered card is also marked "Weak," " Moderate" or " Severe" (based on its numerical value) for determining damage.   Players may have positive or negative modifiers to their draw; for example, having to draw two or more cards and take the lowest or highest card. Players also have a hand of cards, and can play cards from this hand to replace or augment their normal draw.  Hands are replenished and decks reshuffled every turn.

The models are attractive and come in several ranges.  I was playing flaming undead cowboy gunslingers.  My opponent had generically-Asian martial artists.

http://www.wyrd-games.net/community/Ratty-ness/Malifaux/Gameplay/cards.png
Fate Cards
Each model comes with a small card describing its stats and abilities, rather like Warmachine.  These are a handy reference, but have no game mechanical effect.  You neither shuffle nor play them.

Game turns are based on alternating activation.  Each movement and every attack, melee or ranged, is an actions.  Each player chooses a model, performs all its actions, and then the next player chooses a model and does the same.

Whenever a model attacks another, the attacker and defender each draw a card.  The model's statistic is added to the card's value to determine whether the attack exceeds the defense.   If the attack succeeds, then the attacker draws for damage Depending on the amount by which the attacker succeeds, they may draw two cards taking the lowest, one card, or two cards taking the highest.  They then do Weak, Moderate, or Severe damage based on the card.

There are several twists, however.  Players can " cheat"  by playing a card out of their hand, replacing the value.  So if you have a good hand, you can save its cards for your key maneuver.  Players can also (a few times a game based on tokens) play a card in addition to their draw, getting an extra boost.  The suites of cards also can have effects.  For example, for my models, a Ram suite card did extra damage.

Game play proved highly enjoyable, simple on the surface but with considerable depth.  I think a good game is one where the player is presented with interesting, meaningful choices each turn.  Malifaux certainly fulfills this expectation.  Optimal play requires tactical movement and several kinds of resource management.  As a player I had to consider whether to keep or play cards in my hand, and whether to flush or keep my hand, each turn.  The alternating movement required me to anticipate and prioritize each model's actions.  (At one point I rashly charged with a model, and watched it get hit by several other models in return, based on the action sequence and movement.)  Every model had several different capabilities, each good in different situations: I had to decide which one to use, and when.

Normally, I don't like games on the skirmish scale.  (" More death!  Give me more soldiers and more death!")  But I quite liked Malifaux, and look forward to the next game.

Tuesday, July 15, 2014