PERCENTILE SKILL SYSTEM
The following system replaces the normal skill rules from the Phoenix Command Advanced Rules supplement's section 8.2. The remaining skill rules from the rest of chapter 8 (sections 8.1, 8.3 and 8.4) remain in effect as printed.
The basis for the percentile skill system is that it uses a 00-99 roll for skill tests, rather than the 3-18 roll normally used; the main reason for this is to use one system for all skill tests, rather than doing it one way for firearms, but another way for everything else.
Skills range in level from 0 (no skill) to 20 (absolute best), as explained in section 8.1 of the Advanced Rules supplement.
Each skill has a Skill Odds associated with it, which can be found in the Skill Accuracy Level Table (table 1C of the Small Arms Combat System) behind the skill level. Simply use the SAL value from that table as the Skill Odds. This value should be recorded on the character's status sheet for quick reference.
Example: Donovan has Driving skill at level 3, making him a somewhat competent driver. His Skill Odds for driving a car are therefore 9.
When using a skill, the Skill Odds are modified for the situation as deemed appropriate by the gamemaster; see below for suggested modifiers. The final value is cross-referenced with the Burst Elevation column of the Odds of Hitting table (4G) of the Small Arms Combat System to find the Odds of Success.
A 00-99 number is then rolled; if this is less than or equal to the Odds of Success, the skill test succeeds, while if the roll is higher than the Odds of Success, the skill test is a failure. The margin by which the roll makes or fails the test is an indicator of how well (or how poorly) the skill was made.
Interactive Tasks: in a case where two characters are directly opposing each other, subtract the opponent's Skill Odds from the character's Skill Odds. This applies to both characters.
Range, Visibility, Movement, Target Size: when one or more of these factors are important, use the appropriate ALMs from tables 4A, 4C, 4D, 4E (use the Target Size column), and 4F of the Small Arms Combat System as a modifier to the Skill Odds. For example, using Observation skill to try and spot someone who is standing at 25 hexes at night with a full moon has modifiers as follows: –10 for range, –4 for visibility, and +7 for the target size, for a total of –7.
Relative Difficulty: the relative difficulty represents that some tasks are inherently easier or harder than others. It is up to the gamemaster to decide which category any given tasks falls into, but the values below are suggestions. The gamemaster can also choose values in-between those shown to fine-tune the difficulty, if desired.
Extremely Easy: +15
Very Easy: +10
Very Difficult: –10
Nearly Impossible: –15
Example: Donovan is driving his car and encounters a tricky situation. The gamemaster wants him to make an Easy Driving test, which adds a +5 modifier to his Skill Odds of 9, making his total 14. Checking the Odds of Hitting table (4G), 14 gives Odds of Success of 52.
Example: continuing the Observation skill example from above, given a character with level 6 Observation skill, the Odds of Success are 12 (Skill Odds) – 10 – 4 + 7 = 5, for a chance of 19 or less on a 00-99 roll.
In some cases, you will find you need to roll a characteristic instead of a skill — there's no skill for seeing if you can lift a fallen tree off a comrade, but raw strength would come in handy, for example.
In these situations, assume a characteristic has a "Skill" Odds associated with it equal to the characteristic value. For example, if you have a Strength of 11, your Skill Odds with it are 11 as well, giving a chance of 38% of accomplishing the task. Characteristic rolls are modified just as skill rolls are.
Characteristic Rolls in Place of Skill Rolls
Players may want to make rolls using their characteristics instead of using a skill, for example when they don't have the appropriate skill for task. In such cases, use the rules above but halve the characteristic value (round down) to find the Skill Odds.
Example: Figuring out how to wire up explosive charges would need Demolitions skill, but lacking that you could try using Intelligence instead. If you have Intelligence at 17, your Skill Odds would be 17 ÷ 2 = 8.5, rounding to 8, plus any other modifiers that might apply in that particular situation.
Although there are rules for sound detection in section 5.3 of the Small Arms Combat System, the following rules can be subsituted for those in order to tie sound detection into the skill system.
The easiest way to do this is to let characters roll a Perception skill check whenever they may hear something important (in a game with a referee, it is best to have the referee roll this test out of sight of the other players). Use all the normal rules for skill checks as outlined above, but apply all the appropriate modifiers from the Sound Magnitude tables on pages 45 and 46 of the Small Arms Combat System. The basic numbers on these tables, such as for Weapon Fire or Combat Actions, are used as modifiers for the skill roll rather than for determining the base chance. Do not use the Sound Detection Chance table on page 47, but rather use the Odds of Hitting table (4G) as for other skill checks.
Example: Josey shoots his silenced pistol at a prison camp guard, in an attempt to take him out without alerting the whole camp to his presence. The other camp guards are in a hut 10 hexes away holding a conversation.
The guards have a Perception skill level of 2, giving them Skill Odds of 7. This is modified as follows: silenced pistol +60, range 10 hexes –24, isolated from sound by light exterior wall –10, normal voice conversation –45. This gives a total Skill Odds of –12, so they will notice the gunshot on a roll of 00 or 01. Good luck to them.
Had Josey used a non-silenced, 9 mm pistol, the +60 would have been a +105 instead, raising the Skill Odds to 33, and meaning the guards would hear the shot on a 99 or less — in other words, automatically.
(It should be noted that the odds of hearing a noise are not exactly the same using this new system, but it is a much easier way than to totally re-write the tables.)
Once a target has been spotted, the above skill rules can also be used for identifying it, instead of the rules in section 6.13 of the Phoenix Command Expansion.
Using the percentile skill rules, each character can learn Identification skills appropriate to what they are trying to identify; examples are Civilian Identification, Police Identification, Military Vehicle Identification, Aircraft Identification, and so on. To identify a target, simply make a skill roll as described above, using all applicable range, visibility, and other modifiers to end up with an Odds of Success against which the character may roll once that Action Count.
How well the roll is made determines how much information the spotter gets. A failed roll means no positive ID could be made ("a guy with a gun," "a car," etc.). This is very much a referee's call, but with only small difference, the information should be basic — but should include whether the target appears to be on the spotter's side or not. Note that this still has potential for causing misidentification, especially if friendlies and hostiles look alike.
At higher levels of success (25 or more), information should be good enough that the spotter has made a definite ID: though the exact type of target may not be known, at least its overall type is known.
At a difference of 50 or more between Odds of Success and roll, the target should be positively identified for what it is, even if it resembles something that's on the spotter's side. For example, an enemy tank's markings would be visible at this success level.
Note that identification is never automatic — characters will have to keep rolling until they succeed at the test, but to reflect the extra time spent, for every previous Action Count a character spent trying to identify a target, add a +1 to his or her Skill Odds. This assumes the character is engaging in other activities at the same time, like aiming a weapon at the target. If the character is devoting all his or her attention to identifying the target (i.e., he or she is spending CA to identify the target), add +2 per CA spent. This bonus is lost when the spotter looks away or is otherwise distracted.