Friday, January 4, 2013

A Distant Inheritance 3


3: design the game mechanics part 2 Target Numbers

Having designed the dice and success mechanics, the next obstacle is setting the target numbers. If the GM wants to stress a Trait where the character is poor then a target number should be 5. Otherwise target numbers should be 10 or 15, with a rare one at 20 to 25. Remember that in an extended conflict those numbers could go up quickly.

If the characters have either time to prepare or to take an extended time on something they reduce the difficulty by 5. If they’re surprised or rushed increase it by 5.

If the characters don’t have the proper tools (for a fight this is a basic weapon and possibly a shield) the difficulty increases by 5. If they have magical tools the difficulty is reduced by 5. (Heavy Armor isn’t better than light armor, or no armor and a shield  – unless the character has the Talent of Armored Combat the armor hinders as much as it helps and matters only for description of the action results. If they _do_ have that Talent they add the usual 1d6 for the advantages of the Armor.)

Generally tripling the variable element adds 5 to the difficulty. Fighting 1 person is base, 3 is +5 difficulty, 9 is +10 difficulty, 27 is +15 difficulty. Going one week on seriously reduced rations is base, 3 weeks is +5, 9 weeks is +10, and going more than half a year with minimal food and water is +15. Etc.

A quick bit of math to show average rolls (and one each die doesn’t translate to a success level, which is why modifying target numbers is more potent).
1d = 3.5 (33% chance of a 5+)
2d = 7 (83% chance of a 5, 17% chance of a 10%)
3d = 10.5 (96% chance of a 5, 60% chance of a 10, 14% chance of a 15)
4d = 14 (99% chance of a 5, 83% chance of a 10, 45% chance of a 15, 12% chance of a 20)
5d = 17.5 (11% chance of a 5, 92% chance of a 10, 70% chance of a 15, 36% chance of a 20, 12% chance of a 25, 1% chance of a 30

That’s a good benchmark for you to chew on when setting target numbers:  the key takeaway is that a 3d6 is ‘Professional’ – it will hit an ‘easy 5’ 96% of the time and a ‘challenging 10’ 60% of the time – and 5d6 is ‘Heroic’ – it will always hit an ‘easy 5’, hit a ‘challenging 10’ 92% of the time.

Once you have 3d6 in a Trait (or a Trait + Talent) you are assumed to have a high degree of ‘Kirkliness’, or the ability to gauge the odds of what you’re trying to do before you do it. The GM will provide you with the difficulty number and even the % chance of you scoring a marginal success. This lets you know when to hold them, when to fold them, when to walk away, when to run and when to cook darn fine chicken. Again, most monsters and creatures will keep the PCs alive after defeat, if only to argue about how to cook them.

Let’s do an extended example with Thorin.
An unarmed Thorin meets up with a Goblin warrior (difficulty number 5). The difficulty number goes up to 10 because Thorin doesn’t have the right tools. That’s Thorin’s 3d6 Warcraft vs. a target of 10, and Thorin has a 60% chance of winning the first exchange. This might actually turn into a fight, since the Goblin may think it has the upper hand, but it is more likely to fall back or run away.
An armed Thorin meets with a Goblin Warrior. Now it’s his 3d6 Warcraft against a target number of 5. This isn’t a fight – the Goblin flees rather than engage an armed dwarf warrior.
An armed Thorin meets with 3 Goblin warriors. Now it’s Thorin’s 3d6 Warcraft against a target number of 10. Again, this might turn into a fight because they might think they have the upper hand, but more likely it’s a stand-off.
An armed Thorin meets with 9 Goblin warriors. Since the adversaries have tripled twice they are now difficulty 15. Thorin has a 15% chance to win the first exchange, and now he’s the one better served by fleeing or surrendering since the Goblins clearly have the upper hand.
An armed Thorin wearing heavy armor meets with 9 Goblin warriors. His talent for Armored Combat increases his Warcraft roll to 4d6, and he now has a 45 % chance to win the first exchange. Again, this might turn into a fight since the Goblins have a little bit of an edge, but Thorin still has good odds.
An armed Thorin wearing heavy armor and carrying Orcrist meets with 9 Goblin warriors. He’s still at the 4d6 Warcraft with his Talent, and carrying a magical tool means the difficulty drops by 5, back down to 10. The Goblins will not engage unless forced, since Thorin has an 83% chance of winning the first exchange.
Thorin, in heavy armor with Orcrist, meets with 27 Goblin warriors. The further tripling of the adversaries has returned the odds to what they were before the magic sword entered the picture, and now we’re at a point where the Goblins might attack, feeling that 27 to 1 odds are in their favor.
Thorin, in heavy armor with Orcrist, meets with 81 Goblin warriors. That’s another tripling of the adversaries and even with Orcrist the difficulty is now 20, so Thorin has only a 12% chance of winning the first exchange. He might be better off fleeing or surrendering.
Thorin, in heavy armor with Orcirst – and backed by his company – meet with 81 Goblin warriors. The Company Inheritance gives Thorin a 2d6 bonus to his action, pushing his warcraft to 6d6. Since 5d6 is the maximum roll the remaining d6 is turned into another 5 point reduction in the difficulty. Breaking this out we now have 5d6 Warcraft against a difficulty of (5 = 1 goblin, 10 = 3 Goblins, 15= 9 Goblins, 20 = 27 Goblins, 25 = 81 Goblins, -5 for Orcist = 20, -5 for the die past 5d6 =) 15. A properly prepared and magically armed Thorin and company have a 70% chance to win the first exchange with a group of 81 Goblins, and it’s highly likely the mass of Goblins will not dare to attack the 13 doughty dwarf warriors.
In fact, if faced with such an assembly it would take 243 or more Goblin warriors to feel confident enough to engage – and that additional 5 points of difficulty reduces Thorin and Company’s chance to win the first exchange to 36%. This only makes sense – at that point it’s close to 20 to 1 odds against the dwarves, which is an awful lot.

But let’s say that Thorin is backed in a corner, and Thorin’s player rolls well – a 22. That a marginal success, and it means that the difficulty drops by 5 for the next exchange. Narratively we can say that Thorin and company engage in a surprise charge, scattering the Goblins, and claim the high ground. The Goblin’s didn’t lose anyone, but it will take a minute for them to get their full forces ready to attack again. That explains why only one third of the goblins attack in the next exchange (explaining the 5 point difficulty drop).
Now Thorin only needs to roll a 15 or better, and he scores a 24. That’s a success of +9 – not quite good enough for a +10 success level but it does make that 5 point difficulty reduction last longer than one round. So the goblins charge but Thorin and Company hold their position, batting aside Goblins with crossbow, axe, hammer and enchanted blade.
In the third exchange the difficulty is again 15, but Thorin rolls a 12. That’s a marginal failure, so the Goblins are able to consolidate their position and launch a real attack. Thorin’s difficulty is back up to 20 for next round only.
The fourth exchange has Thorin roll a 20 exactly, for a marginal success – despite still being deeply outnumbered Thorin and Company continue to hold, battered and bloody but unbowed in the face of the Goblin army, and the Goblins are starting to get demoralized, with two thirds of their number now dead of fleeing.
…And now the tide turns in their favor. At the start of the fifth exchange the Goblin’s lose their one exchange difficulty bonus, so the difficulty drops to 15. Then Thorin adds his one exchange difficulty reduction from the fourth exchange and the difficulty is further reduced to a 10.
In the sixth exchange Thorin rolls a 16, for a +5 victory, again reducing the long term target number to 10. The mass of Goblin troops is in disarray, with only 9 of them still in any position to fight. This conflict is pretty well over, and the mass of goblins flees rather than continue it. It’s likely one third of the goblin force is actually dead from this battle, but it would be unseemly to count the bodies. Regardless of how many are still alive it is a heroic 20 to 1 victory for Thorin and Company, and done without meaningful losses. The example also shows how important that first exchange is in setting the fight’s trajectory.