Radiation: variant rules

[Lane Shutt]

I'm still working out the actual effect of radiation expressed in D20 stats but the system is ready for player input.

The present rules for Radiation have one major fault - a high level or lucky character can avoid any damage. By using a fixed DC save throw taken periodically they ignore the cumulative nature and increasing severity of radiation damage. The reality is that people experience the physical effect of radiation exposure gradually unless subject to a large dose in a short time. As their dose increases the effects become progressively more severe, from slight nausea to dead in D6 days. While the onset effects occur over a range of absorbed dose at some point everyone will suffer some effect.

----------updated 5/21--------------------------------

The (My) solution to this shortcoming is to track radiation exposure and make make periodic saves with DC and effects based on current exposure levels. The basics, for your review, are as follows.

New stat: Radiation Dose (RD) represents the amount of radiation exposure and resultant biological damage the character has sustained.
This exposure is measured in centiGray (cGy) which is approximately the amount of radiation absorbed, by an average person, per year. Given time the character may recover from some or all damage, reducing their RD.

Taking radiation damage: Any time a character is exposed to radiation he may be required to make a saving throw to avoid the effects. The characters RD is compared to table ### to determine the save DC and effects. Saving throws are normally mare every 20 cGy or once per hour, whichever is longer.
If their new RD exceeds the upper limit of any dose range they will automatically suffer the effects of that range with no save.
If the characters RD increased by less than 100 cGy in the last hour use the Save DC for the lowest range their RD falls within.
If their RD increased by 100 cGy or more, such as an instant source, use the DC for the highest range they fall in. Failing a save causes the character to suffer the effects of that and all lower ranges. Even if they pass the save for doses greater than 100 cGy they must still save vs any lower ranges.
Note - once a save is failed for a dose range no saves are needed until reaching the next higher range.

Ex: Sgt. Jones had an RD of 460cGy and received a dose of 70cGy in the last hour. He was not suffering from the 50-500 effects but since his new RD is 530cGy he will now. The dose was less than 100 so he saves vs DC 20 for the 300-800 range. He passes the save so only suffers minor effects. Later that day a Nuke goes off nearby and he receives an instant 700cGy raising his RD to 1230. He passes the (DC 35) save for the 1k-3k range but fails the save for 500-1500. He now suffers from severe symptoms and any non overlapping effects from lower ranges. He should probably head to the nearest Radiation Ward and spend a couple years away from nukes.

Sources: guidelines will be provided for persistent and instant sources. A persistent source, such as fallout or unshielded warheads, will have a dose/time. Instantaneous sources like nuclear detonations and particle weapons will have a step increase in dose.

Effects: these are approximate numbers but should give an idea of the overlap of severity levels.

Level       RAD      DC      Effect
minor      50-500   10-15    minor nausea, fatigue, low chance of death
moderate   300-800  15-20    nausea, exhaustion, 50%+ death
severe     500-1500 20-25    slow (D3+2 weeks) death
screwed    1k-3k    35       death in D3 weeks
Dead Meat  2.5k+    40       death in D3 days

Note - similar effects are not cumulative, exhaustion replaces fatigue etc.

Skill checks: negative modifiers at each severity level

Death: each severity level will have primary damage of Dx Con loss, secondary damage will be 1 pt Con loss at XX interval. Saving vs secondary damage will stop Con loss and prevent death.

Healing: each week with no radiation exposure will automatically reduce the RAD by a fixed amount. This may be modified by high/low Con. Lost Con is recovered weekly once you stop taking damage and not exposed to radiation.

Anti Radiation Drugs/ Medical Treatment: rather than miracle healing these will reduce the Save DC.

Shielding: vehicle armor will reduce any dose received. Most likely mechanic will be to divide the Dose by the Armor Hardness plus one. Dedicated shielding and structures will also have values assigned. Distance will also reduce the dose received.
Equipment: some changes to equipment stats and function would be made.

Damage to vehicles: Radiation has different effects on equipment than human bodies. Instead of cumulative damage to tissue it interferes with electronic systems, these will have a chance of failing or degraded performance based on radiation levels and hardening.

--------------------------------------------------

These rules should not scare characters away from encounters with radiation or using nukes, the saves and damage can be endured at low exposure levels, but they will have to be more cautious. Nuking downtown then rushing in to rob the bank vault is probably not a viable plan.


Comments?
Too Complicated?
Anything unclear?

 

[Draco Argentum]

That could be workable and dosen't seem over complicated to me.

Screwed and dead meat overlap in terms of RAD AtM.

 

[Golem2176]

Hmm, with a little tweaking I could use this for Rad fallout rules for my Mystara campaign. Thanks!

 

[Elfman]

Great rules overall. I have a few suggestions/comments:

The (My) solution to this shortcoming is to track radiation exposure and make make periodic saves with DC and effects based on current exposure levels. The basics, for your review, are as follows.

New stat: Radiation Absorbed Dose. Not to be confused with the real world unit of measure. This is used to track a characters current level of radiation damage.

I agree that the name could be a source for confusion, so why not just call it RA instead of RAD? Then you can talk about both without confusing them.

You should also clarify that RA is tracked just like damage. It goes up when you are exposed to radiation, and goes down at a set number per week. What is that number, by the way?

Saving throws would be made at increments of 10-20 units or once per hour, whichever is longer, or any time an instant dose greater than xx is received.

Make these the same for simplicity sake. Make one saving throw every 20 units, whether those units come all at once or 1 at a time. To make it more deadly (if that's what you wanted) you could force multiple saves when an instant dose is a multiple of 20. So if someone took 100 RAs of damage, he'd have to make 5 saves in a row. Or to make it a little less deadly, increase the DC of the save by 1 for every full increment of 20 RAs taken in an instant dose.

Effects: these are approximate numbers but should give an idea of the overlap of severity levels.

Level       RAD      DC      Effect
minor      50-500   10-15    minor nausea, fatigue, low chance of death
moderate   300-800  15-20    nausea, exhaustion, 50%+ death
severe     500-1500 20-25    slow (D3+2 weeks) death
screwed    1k-3k    35       death in D3 weeks
Dead Meat  2.5k+    40       death in D3 days

Effects are applied once you fail a save for that level or you reach the top of it's range. The next check will be at the following levels DC. If below the next level no checks are made until you reach it.

Skill checks: negative modifiers at each severity level

Death: each severity level will have primary damage of Dx Con loss, secondary damage will be 1 pt Con loss at XX interval. Saving vs secondary damage will stop Con loss and prevent death.

Healing: each week with no radiation exposure will automatically reduce the RAD by a fixed amount. This may be modified by high/low Con. Lost Con is recovered weekly once you stop taking damage and not exposed to radiation.

Anti Radiation Drugs/ Medical Treatment: rather than miracle healing these will reduce the Save DC.

This is all good. Figure out the XXs, and it's great.

Shielding: vehicle armor will reduce any dose received. Most likely mechanic will be to divide the Dose by the Armor Hardness. Dedicated shielding and structures will also have values assigned. Distance will also reduce the dose received.

Armour should reduce RA by dividing the total by (Hardness +1). This way, something with a 1 hardness would still offer some amount of protection.

Again, overall great stuff. I really like these rules!

 

[Draco Argentum]

To make it more deadly (if that's what you wanted) you could force multiple saves when an instant dose is a multiple of 20. So if someone took 100 RAs of damage, he'd have to make 5 saves in a row. Or to make it a little less deadly, increase the DC of the save by 1 for every full increment of 20 RAs taken in an instant dose.

I'd take the second option, less die rolls is a good thing IMO.

 

[Lane Shutt]

Screwed and dead meat overlap in terms of RAD AtM.

The overlap is intentional, in fact all ranges should have some.
One problem in assigning damage is the tables I'm working from have non overlapping dose ranges but effects do overlap.
For example 150-300 nausea in 20-70% death in 10%, dose 300-500 nausea in 50-90% death in 10-50%.
Based on this someone with a dose of 200 could die and another person with dose 400 might not feel any effect. However at a dose of 800 everyone will feel nausea at minimum.

How is this?

Change RAD to RD for Radiation Dose, the unit of measure is the centiGray (cGy) which is a real world measure for radiation exposure. In the real world 1 cGy is approximately the amount of radiation absorbed, by an average person, per year.

Saving throws are normally made every 20 cGy at a DC determined from table xx. Normally the lowest range, which their RD matches, is used. The exception is any instant dose of 100 cGy or greater. The sudden shock to the system causes them to save vs the highest effect their RD is in range. Failure applies the effect for that range and all lower ranges. A successful save still requires saving throws for lower effects, if any.
Once they fail a save no rolls are made until reaching the next higher range. If at any time your RD exceeds a range, without failing a save, its effects are applied immediately.

Healing: Each week with no radiation exposure will automatically reduce the RD by 10 cGy + Con modifier and heal one point Con damage.

 

[Kraken]

The rules llok good so far. From my very limited understanding (couple of physics courses) it seems a more realistic framework than the system in the main rulebook. That was one of the things I found disapointing about the rules was the extent of effort put into developing (fairly) realistic rules for combat, weaponry, etc. and the lifting the basic disease/poison rules from the D20 core rules (which are pretty unrealistic).

One of the things I think is required for diseases and poisons is onset times and continual damage (over period of time) instead of the you are poisoned and two rounds later there are no further effects.

I have been trying to develop my own set of generic rules (for any D20 setting) for poisons, diseases, drugs, etc. Unfortunately my knowledge of actual realworld effects is fairly limited and I find it hard to research topics like chemical weapons and poisons over the web these days (like to be branded a terrorist any one?).

Overall well done on the rules, Lane Shutt and I await in anticipation further releases.

 

[Draco Argentum]

Saving throws are normally made every 20 cGy at a DC determined from table xx. Normally the lowest range, which their RD matches, is used. The exception is any instant dose of 100 cGy or greater. The sudden shock to the system causes them to save vs the highest effect their RD is in range. Failure applies the effect for that range and all lower ranges. A successful save still requires saving throws for lower effects, if any. Once they fail a save no rolls are made until reaching the next higher range. If at any time your RD exceeds a range, without failing a save, its effects are applied immediately.

Healing: Each week with no radiation exposure will automatically reduce the RD by 10 cGy + Con modifier and heal one point Con damage.

I like this since it covers the cumulative nature of radiation.

Does this: "A successful save still requires saving throws for lower effects, if any."

Contradict this? "If at any time your RD exceeds a range, without failing a save, its effects are applied immediately."

It seems that they could be contradictory, or perhaps the first quote means lower effects in this range?

 

[Lane Shutt]

Tried to clear things up a bit more and edited the original post to reflect the changes.

one of the things I found disapointing about the rules was the extent of effort put into developing (fairly) realistic rules for combat, weaponry, etc. and the lifting the basic disease/poison rules from the D20 core rules (which are pretty unrealistic).

One of the things I think is required for diseases and poisons is onset times and continual damage (over period of time) instead of the you are poisoned and two rounds later there are no further effects.

The Chem, Bio, radiation rules were IIRC in the last playtest pack so there was less time to review them. At first glance the numbers looked good, the relative DCs are reasonable and damage is of the right type. The problems are the mechanism and agent persistence. My brother and I are working on better rule mechanics and stats.

Expect primary save in xx time, secondary zz time. Some will have damage/ time instead of primary or secondary.

Trust me, the chemical rules will be annoying to protected troops and deadly to unprotected troops.

I have been trying to develop my own set of generic rules (for any D20 setting) for poisons, diseases, drugs, etc. Unfortunately my knowledge of actual realworld effects is fairly limited and I find it hard to research topics like chemical weapons and poisons over the web these days (like to be branded a terrorist any one?).

We are focusing on Chemical and Radiation but will have some biological weapons as well. While some of the equipment will be tailored to the 2089 setting the rules will be generic.

Research online is not a problem for me, all mine has been from a single website. I'm a registered user and chemical weapons is a valid topic for anybody in the military.

 

[Draco Argentum]

Cool, its clearer now and the example helps a lot. I think its coming together well. The way effects are handled seems to mimic what I know of radiation sickness well enough for for an RPG.

 

[Golem2176]

Thanks for the updates and clarifications! Any chance of a small (pdf) guide/book on how to apply this knowledge on a larger scale? Like waht would happen if there was stellar fallout?

 

[Lane Shutt]

I still have a few things left on this project.

Describing the physical effects in game terms.

List of exposure levels from various nukes and other sources like fallout. Effectiveness of shielding will be done at same time. I will also try to find some data on radiation levels in space.

Large scale effects. Where does the fallout land and how long it lasts. How to handle units (mass combat level) based on exposure levels.

Equipment, both new and converting existing gear.

When I've pulled out all my hair, from reading the very dry source material, and the chemical weapon rules are done we plan on submitting them to Mongoose. With what I have so far it could be split into S&P articles or a small PDF.