After having read (half) the PDF of Tales from the Loop (TFL), I’ve had a few remaining thoughts about the Year Zero Engine.
Conflict Without Combat
Since the focus of TFL is Kids having Adventures
rather than murderhobos adventurers questing for loot,
TFL is a bit of an outlier among Year Zero Engine games.
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When Kids get into “Trouble”, they always roll unopposed. The GM never rolls dice for NPCs. NPCs don’t even really have attributes, save in a few cases mentioned below.
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Most incidents require only one die roll to resolve. A complicated incident, where one Trouble leads to another, might require a few die rolls to resolve each challenge. The rules also define Extended Trouble, which require the Kids to accumulate some number of successses defined by the GM, usually as a multiple of the number of players, using a GM-defined mix of skill rolls. (A comparison to D&D 4th edition “skill challenges” is inevitable.)
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As consequences of Trouble, Kids may acquire up to four Conditions, each of which subtracts a die from subsequent tests. The fifth condition is Broken: all tests automatically fail, and the best a Kid can do is limp home to nurse their mostly metaphorical wounds. (Things from the Flood apparently has rules for more lasting, possibly permanent consequences.)
The net result is that TFL lacks “combat” as most RPGs define it. Kids get into fights with each other, but the results are a few bruises and hurt feelings. With stakes so low, TFL doesn’t need to track rounds or “initiative”, especially with players making all the rolls. The GM sets the scene, the players describe what they’re doing, the dice decide how well or badly they’re doing it as necessary, the GM describes how that affects the opposition (human, mechanical, or natural), and the cycle repeats.
TFL isn’t really my cup of Ovaltine. But I really appreciate an RPG in which player characters aren’t in life-or-death circumstances, much less seeking to kill things and take their stuff1. Taking a minute or more of play for each second of “combat” sometimes feels like a waste of time, even in “rules light” systems.
Difficulty Factors
The Year Zero System’s central mechanic – roll a pool of six-siders, at least one six is a success – already skews against success. Unlike most systems, TFL has little need to define difficulty factors. Non-player characters and machines are merely narrative devices, usually with no associated characteristics.
However, the GM may require two or even three sixes on the dice to overcome a specific Trouble. (Two is “Extremely Difficult”, three is “Almost Impossible”.) A few NPCs may have “special attributes” that indicate certain kinds of Trouble require extra successes. For example, a robot may have Powerful Hydraulics 2, which means any Kid who pits their own strength against the robot must have two successes to win. In one of the Mysteries that make up more than half of the book, a particular crowd requires 3 successes to push through.
So, how difficult is Extremely Difficult or Almost Impossible? As usual, I turned to programming to understand a tabletop game, and came up with this chart.
Dice | Normal | Extremely Difficult | Almost Impossible |
---|---|---|---|
1d | 16.67% | 0.00% | 0.00% |
2d | 30.56% | 2.78% | 0.00% |
3d | 42.13% | 7.41% | 0.46% |
4d | 51.77% | 13.19% | 1.62% |
5d | 59.81% | 19.62% | 3.55% |
6d | 66.51% | 26.32% | 6.23% |
7d | 72.09% | 33.02% | 9.58% |
8d | 76.74% | 39.53% | 13.48% |
9d | 80.62% | 45.73% | 17.83% |
10d | 83.85% | 51.55% | 22.48% |
11d | 86.54% | 56.93% | 27.32% |
12d | 88.78% | 61.87% | 32.26% |
13d | 90.65% | 66.35% | 37.19% |
14d | 92.21% | 70.40% | 42.05% |
15d | 93.51% | 74.04% | 46.78% |
16d | 94.59% | 77.28% | 51.32% |
17d | 95.49% | 80.17% | 55.65% |
18d | 96.24% | 82.72% | 59.73% |
19d | 96.87% | 84.98% | 63.57% |
20d | 97.39% | 86.96% | 67.13% |
Short answer? Pretty damn hard.
Even with rerolls from pushing and Luck Points (another TFL thing), even competent Kids will struggle. For example, say a Kid would roll 6 dice for Trouble, which puts their chance of success at 67%. This drops to 26% for “Extremely Difficult” and 6% for “Almost Impossible”. If they pushed that roll – about equal to rolling 12d – chances would rise to 62% and 32%, respectively. Pushing an Almost Impossible roll and using a Luck Point – perfectly legal, if I read the rules right – puts the Almost Impossible at 60% (equivalent to rolling 18 dice).
With enough dice, the Almost Impossible becomes doable … but to get those dice one must gain a Condition and/or lose a Luck Point, of which the average kid has 32. And what about the next Trouble?
Other Year Zero games subtract 1-3 dice from the dice pool to reflect difficulty. As far as I can tell, TFL doesn’t. Number of successes is a very coarse-grained mechanic; as the sole difficulty gauge it may be simpler and less arbitrary but some GMs may miss the fine control.
So?
If I’m probably never going to play this game, let alone run it, why take an entire blog post to analyze probability curves and rules?
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Tales From The Loop did win five ENnie Awards, including Best Game and Product of the Year. While much of that could be attributed to the art and nostalgic setting, I have to assume the rules – all 20 pages of them – played some part.
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At some point I’d like to write my own RPG, possibly involving dice pools. TFL implements my prior ideas of having players roll all dice, of having the PCs drive the action, and of defining most NPCs as obstacles rather than independent actors.
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It’s interesting to me how the choice of theme, genre, and setting allowed the designers to radically streamline their rules. Most notably, limiting negative consequences for Kids to Conditions that can be removed in the next few scenes does remove the need and urgency for complicated combat systems in all but the most competitive and rules-lawyery player. It’s a trick I’m trying in the astral plane rpg that I’m mostly not writing: being non-corporeal, astral beings can be “knocked out” or restrained relatively easily but permanently harmed in only a few specific ways. (Just like Kids and their seeming immortality3.)
Ultimately TFL demonstrates how few rules an RPG really requires. All but about 20 pages of the rules are background, description, adventure hooks, and fully worked adventures. Over half the 190+ pages are the Mysteries themselves, which but for a few scattered special attributes consist entirely of exposition, maps, diagrams, and NPC profiles in purely descriptive terms.
Program Listing
Most of this should be familiar from
a previous article.
Note that I’m using a different and faster defiinition of choose()
.
#!/usr/bin/env lua
-- Chances of success on a single die
local SUCCESS = 1/6
local function choose(n, k)
if n < 1 or k < 0 or k > n then
return 0
end
local result = 1
for i = 1, k do
result = result * (n + 1 - i) / i
end
return result
end
local function binomial(n, k, p)
return choose(n, k) * (p)^k * (1-p)^(n-k)
end
-- chance of rolling at least `k` successes on `n` dice
local function success_at_least(n, k)
local result = 0
for i = k, n do
result = result + binomial(n, i, SUCCESS)
end
return result
end
local function format_percent(p)
return string.format(" %5.2f%% ", p * 100)
end
local function print_table(maxdice)
local md = (maxdice or 10)
local rowbuf
-- print header
rowbuf = { "Dice ", " Normal ", "Extremely Difficult", "Almost Impossible" }
print(table.concat(rowbuf, '|'))
rowbuf = { ":---:" }
for n = 1, 3 do
table.insert(rowbuf, "-------:")
end
table.insert(rowbuf, "")
print(table.concat(rowbuf, '|'))
-- print each row
for n = 1, md do
rowbuf = { string.format(" %2dd ", n) }
for k = 1, 3 do
table.insert(rowbuf, format_percent(success_at_least(n, k)))
end
table.insert(rowbuf, "")
print(table.concat(rowbuf, '|'))
end
end
print_table(20)