Ten Dead Rats Rules Update

I have finally figured out what was broken in the ambition based XP calculations in Ten Dead Rats. I was pretty confident in the logic and math that I used to create the formula for calculating ambition award amounts, but for some reason it came out wrong at the table. Which is pretty weird given that I back-calculated the math from the numbers I wanted to use at level 1, which is the level my party is at right now. The problem, it turns out, was the extra bit I added to try and keep it simple on the page.

It starts with my XP chart, whose origin begins with the OD&D fighter level chart. It’s basically a progression of factors of 2 times 1,000 — 2k, 4k, 8k, etc. For some reason OD&D breaks this at 8th level, using 120k instead of 128k and then 240k instead of 256k. I’m not sure why, but that’s neither here nor there. Point is, I stole the OD&D fighter chart, reverted it to a regular doubling pattern throughout, and then dropped a zero off the end. The decision for the last part was based on using treasure based XP, to keep the progression in scale with reasonable numbers for the Warhammer economy. At 2nd level, 200 gold crowns is definitely a fortune, while 2,000 gold crowns is kind of unimaginiable wealth.

So, the next step was figuring out how much XP to give for each ambition. It had to scale up as the party levels, and my basis for figuring it out was answering the question, how much XP does a player need before they gain a level? I figured a party ambition should be a really big deal, so maybe it gets you halfway there, while a personal ambition should be less, so maybe a quarter of a party ambition, or 1/8th the way to your next level. The formula therefore became:

(XP for Next Level – XP for Current Level) / Ambition Factor

Where “Ambition Factor” is 2 for a party ambition or 8 for a personal ambition. This is OK, but felt a bit complex to write into the rules. Then I noticed that since the XP per level chart doubles every level, I could double the Ambition Factor and then just use XP for Next Level rather than using the delta between levels. This basically works – except at 1st level. And the reason is, the delta between levels does not double from level 1 to level 2. Let’s look at the XP chart and fill in the delta values:

Level XP Delta from Previous Level
1 0
2 200 200
3 400 200
4 800 400
5 1,600 800
6 3,200 1,600
7 6,400 3,200
8 12,800 6,400
9 25,600 12,800
10 51,200 25,600

As you can see, the delta value for both level 2 and level 3 is actually the same — 200 XP. How could I fix this? I toyed with actually mucking with the XP per level chart. I could set level 2 to 100 XP, and then double the delta each level, so 300, 700, 1500, 3100, etc. That would probably be OK, and I don’t mind actually having slightly lower numbers, though the factors of 2 sequence really appeals to the software engineer in me and I like it being obviously derived from the OD&D fighter chart. I also kind of don’t want to screw with the players of the current stream — lowering the XP to level 2 would likely cause some of them to suddenly jump a level.

Another option would be to actually write out the real formula above — calculate the delta and stop doubling the ambition factor. I like the idea of the rules having less abstraction from the original design, but it’s a kind of complicated thing to ask readers to do. I definitely prefer a presentation that favors a simple single-operation formula.

So finally where I ended up was to simply special case level 1. Doing this also lets me use current level XP instead of next level XP as a base and cut the ambition factor in half for slightly easier math. I couldn’t do this before because level 1 starts at 0 XP. The text therefore now includes this chart for ambition based XP awards:

Ambition Expected Duration Example Bonus XP Sole XP
Personal 2-3 sessions Purchase a firearm
Make contact with a thieves’ guild
Unveil a chaos worshipper
25 Level 1: 25 Thereafter: Current Level XP / 8
Party 6-12 sessions Travel from Altdorf to Kislev
Find proof that Skaven exist
Find out who is behind all these murders
Level 1: 100 Thereafter: Current Level XP / 2

That should give accurate numbers and is hopefully easy for readers to parse. And it is ultimately accurate to the original design I was shooting for. I’ve updated the PDF and incremented the version number to 1.2. You can get it here:

Ten Dead Rats

6 thoughts on “Ten Dead Rats Rules Update

  1. Hey Paul,

    This is a really interesting project, and I’ve been working on something somewhat similar. I can’t find rules about how talents are gained. Will you have characters buy them or just get a new one per level?

    1. Page 6: “Players can select one Talent per level including their first.”

      Though I also think access to a free talent is a great idea for magic items.

  2. Speaking of talents and errata. I am building an excel sheet to generate 10dR characters and in the process I have some questions notes.
    -So it looks like “Magick” is a prerequisite for “Spell” and Magick can not be taken until 2nd level. (I Guess you can take Spell at 1st level, it jsut wont do you any good until you take Magick.

    -Stone Soup is listed after the Strike talents.
    -Read/Write is still listed under Academic Careers even though they are now a given.
    -Soldier has ‘Fleet!” as a talent instead of either Flee! of Fleet Footed

    This has also inspired me to kit-bash my own micro system.

    1. Awesome! Would love to see what you come up with. Good catches on the various typographic errors, I will take a pass at cleaning those up.

      “Magick” is indeed a pre-req for Spell, but it should be available at 1st level. I assume you’re referencing the ruling of “you cannot have dice equal to or in excess of half your level”, and then the example of 5th level being limited to 2 dice. Presumably by this math level 1 rounds down to 0 dice, which is not what I intended.

      I’m now considering changing this to say “You can take this talent multiple times, but no more than once per 3 levels of experience. So at level 4 it can be taken twice, at level 7 three times, etc.”

      Also be aware that taking Magick gives you a free spell. My intent here was definitely that a starting out character could be casting a spell right away at first level.

      1. I’m also a little conflicted about removing Read/Write from the Academic lists, even though it is given for free. I’m not sure if removing it from the list makes it more or less confusing.

        1. Thanks for responding.
          Yeah, I had assumed that was the intent for Magick/Spell, but was not sure.
          The typos are the kind of thing I would only notice as I was setting up tables.
          I ended up putting an * next to Read/Write on those lists as a reminder to myself.

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