Omnifray RPG

Frequently Asked Questions 1 to 8

This page is intended to answer genuine frequently asked questions. I'm looking for questions that critics have posed in reviews, questions that have come up time and time again from players, that sort of thing. I've also included a few questions which the other FAQs naturally lead on to.

1. What do my ability scores mean? How good is a score of 6 or 10 or 20?

2. How did you come up with the numbers on the Simple Action Resolution Table?

3. What does a difficulty score mean? How difficult is a task with difficulty 2 or 10?

4. What's the point of the Simple Action Resolution Table (the SART)?

5. What is the main advantage of the way the Simple Action Resolution Table works?

6. But the values on the Simple Action Resolution Table aren't intuitive!

7. What about the numbers on the Basic Speed of Action Table?

8. How do the Speed of Action numbers compare to the SART numbers?

9. What's the easiest way to use Omnifray task resolution in practice?

The answers to these questions are connected and are actually very simple. 

Short answers:-

 (1) What do my ability scores mean? How good is a score of 6 or 10 or 20?

An ability score of 6 is typical for an average man; an ability score of 8 is twice as good, 10 is four times as good, 12 is eight times as good, etc., so +2 ability score = being twice as good. (A score of 20 is over a hundred times better than an average man's, so it's pretty phenomenal.)

(2) How did you come up with the numbers on the Simple Action Resolution Table?

The percentage scores on the Simple Action Resolution Table are the numbers that you need so that a 2-point difference in ability score gives you twice as good a ratio of successes to failures in a basic task, assuming that equally matched characters are equally likely to succeed.

The Simple Action Resolution Table can be reconstructed with simple maths if you really want. 

(3) What does a difficulty score mean? How difficult is a task with difficulty 2 or 10?

A difficulty score is just like an abiity score except that it represents the difficulty of a task and not the concrete ability of a particular character. A difficulty score of 6 for a basic task means that an average man has a 50% expectation of success. Difficulty 2 gives him 20%. Difficulty 10 gives him 80%. +2 to the difficulty score halves your character's ratio of successes to failures. (If you like, it doubles the ratio of successes to failures that the TASK has for defeating the CHARACTER.)

(4) What's the point of the Simple Action Resolution Table?

Using the Simple Action Resolution Table means that no matter how good your ability scores are, an increase of +1 to an ability score has basically the same practical value for your character in real terms because it has a constant impact on his ratio of success to failure.

(5) What is the main advantage of the way the Simple Action Resolution Table works?

Because a +1 boost to any ability score has the same practical value for you no matter what your ability scores may be, ability scores and traits can have a constant value (in character generation points), and you can choose your character's feats, without totally screwing up game-balance.

(6) But the values on the Simple Action Resolution Table aren't intuitive!

Yes they are, once you undestand the principle behind them. Besides, most of the game will involve Advantages between -8 and +8, and by coincidence the Simple Action Resolution Table has a pretty memorable pattern in that range:- 50% +9% +8% +7% +6% +5% +4% +3% +2%. So for instance if your Advantage is 2 your success chance is 50% +9% +8% = 67%. If your Advantage is minus 2 (a Disadvantage of 2), your success chance is similarly 33% (i.e. 100% minus 67%). Easy.

This means that when I'm playing or reffing Omnifray, I often don't even need to look at the SART.

(7) What about the numbers on the Basic Speed of Action Table?

A +4 boost to your Alacrity halves the time it takes you to complete an action. The dice used have to be different for different scores so that there's always a reasonable element of randomness to how long an action will take.

(8) How do the Speed of Action numbers compare to the SART numbers?

Imagine you are fighting an opponent and your Alacrity is 4 points better than his. You get to strike at your opponent twice for every time he strikes at you. Now imagine that you have a 2-point Advantage for hitting your opponent and a 2-point Advantage for defending against his blows. You have a base 67% hit chance against him, and he has a base 33% hit chance against you. You get to hit your opponent twice for every time he hits you. So have two 2-point Advantages has similar impact to having +4 Alacrity. The comparison is FAR from perfect but it represents an ATTEMPT to tie the two systems in with each other as far as possible.

(9) What's the easiest way to use Omnifray task resolution in practice?

For opposed tasks, you compare the opposing character's ability scores and use Simple Action Resolution or the Rough & Ready version of Four-Tier Action Resolution. For unopposed tasks, decide what chance of success an average man would have. Pick a percentage from the Simple Action Resolution Table. Then compare the character's ability score to an average man's score of 6 (or 10 for Target if that's the relevant ability score). However many points better or worse the character's score is, move up or down that many rows on the table and pick the percentage success chance from the row you reach. It's really very, very easy to do (though not quite so easy to describe without having a table to point at). (If a row on the table covers several Advantage scores, obviously you count it as several rows.)

Long answer to questions (1) to (3):-

For any ability score apart from Target, an ability score of 6 is what you would expect for an average man, meaning, if you want to be pedantic, the median average for an adult male human. (Target is simply 16 minus your Size for most people and it's down as a separate stat to make missile combat run quicker.)

So, if your ability score is 6, it's typical for an average man. It says so in the Basic Handbook.

Using the simplest mechanic in Omnifray ("Simple Action Resolution"), when two characters oppose each other in a straightforward contest, if they have equal ability scores, they each have a 50% chance of success. That's rather what you'd expect, isn't it?

For every extra +2 points of ability score that you have, your ability score is twice as good in a very particular sense:- for a basic task handled via Simple Action Resolution, your ratio of successes to failures doubles for every extra 2 points of ability score that you have. That's worked out for you via the Simple Action Resolution Table so you don't actually have to get into the maths yourself.

So, if your ability score is 8, it's twice as good as an average man's, in the sense that your ratio of successes to failures for a basic task is twice as good as an average man's.

For instance, suppose the task in question is to convince a particular non-player character that your intentions are friendly. The ref decides to treat this as a basic task handled via Simple Action Resolution. He deems that an average man standing in your character's shoes would have an 11% chance of success. That is, roughly, a ratio of 1 success to 8 failures. The average man's relevant stat would be his Manipulation score of (big surprise here) 6.

Now suppose you have a Manipulation score of 10. That's 4 points better than an average man's, or twice +2. So, starting from a ratio of successes to failures of 1:8, your ratio of successes is doubled twice. That makes your ratio of successes to failures 4:8 or 1:2, which gives you roughly a 33% chance of success.

As I say, you don't need to do this maths to play the game. The ref simply decides that an average man has a success chance of 11% (picked from the percentages shown on the Simple Action Resolution Table or SART), notices that your Manipulation score is 4 points better than an average man's and counts up 4 rows on the SART from 11% (skipping 15%, 20% and 26%) to arrive at 33%. Another way of going about it would be to say that an average man has a success chance of 11% which means that the difficulty score is 12 (because that gives the average man a Disadvantage score of 6, worked out as 12 minus his Manipulation of 6). From that difficulty score of 12 you subtract the player character's Manipulation score of 10 for a total Disadvantage of 2. The SART shows 33% success chance for a Disadvantage of 2.

Difficulty scores work just like ability scores - the only difference is that they represent the abstract difficulty of a task, rather than any actual character's ability. So a basic task using Simple Action Resolution with a difficulty score of 6 is one which an average man could succeed at roughly half the time. A two-point increase in difficulty score will double any character's ratio of failures to successes at that task.

Thus suppose the referee decides that your character has an 11% chance of success at a particular task. You fail, but the ref lets you try again, this time increasing the difficulty score by 2 points because you've already failed once at the task. (That might or might not be fair but it's the ref's call, plainly.) With an 11% chance of success, your ratio of successes to failures was roughly 1:8. Now it's going to be roughly 1:16. You will have a success chance of one in seventeen (i.e. out of 17 hypothetical attempts you would get 1 success and 16 failures). Where you previously had an 11% chance of success, you now only have a 6% chance of success.

Again, you don't do this maths when you're playing Omnifray. The Simple Action Resolution Table does it for you. It's a beautiful table. Having the SART means you never even have to think about the underlying mathematics. You can and should feel free to play Omnifray proceeding on the footing that there is no underlying maths and you are just picking numbers off a table. On the other hand, if you are interested in mathematics, the formula is obvious:- C=1/(1+2^(0-A/2)) where C is your chance of success, A is your Advantage score, / is the divisor sign and ^ is the sign for "to the power of". (This is BASIC notation.)

If you want to be tricky about it, there are a couple of things you could ask. First, what about tasks which aren't handled via Simple Action Resolution? Four-Tier Action Resolution is basically the same as three lots of Simple Action Resolution, and for each one that succeeds, you get a third of a success. The result is then a modest, clear or critical success, i.e. 1/3, 2/3 or 1. Obviously, the statistical probabilities are compounded, but they are built on the same basis as above. Then there is Differentiated Action Resolution, which for example could result in an average man (with a Perception of 6) finding 11% of the coins strewn about in long grass, but a player character with a Perception of 8 finding 20% of them. That follows the same basic structure but translated into degrees of success instead of chances of success. Weighted Action Resolution twists the probabilities for things like contests of pure brute strength, which are less influenced by random factors. It's basically like any other form of action resolution but you multiply the character's Advantage score by a weighting. So a weighting of x4 for Strength contests gives a 2-point difference in Strength the same impact as an 8-point difference in ability scores normally, altering your ratio of successes to failures by a factor of 16 (worked out as 2x2x2x2). It's still better to think of your character being twice as strong as an average man if your character has a Strength of 8. It just means that in a tug of war against an average man you will be 94% likely to win. If you are supposed to be in some sense twice as strong as your opponent, even for a game of fantasy that seems fair!

In other words, most of the Omnifray mechanics (even including damage / percentage injury)  are built around Simple Action Resolution, meaning that they are variants of it in one way or another. So a difficulty score of 6 means more or less the same thing in Simple Action Resolution, Four-Tier Action Resolution or Differentiated Action Resolution. It means that an average man has a 50% chance of success, or three 50% chances of cumulative partial (one-third) success, or an expectation of roughly a 50% degree of success. His expected degree of success is 50%. Weighted Action Resolution obviously skews things in favour of a character whose ability score is better than the difficulty score, and against one whose ability score is worse than the difficulty score. Anyway Weighted Action Resolution is rare except for contests of pure brute strength.

Another thing you could ask is - what if my ability score is 1 point better than an average man's, or 3 points better, etc.? Well, it's a smooth probability curve, so a 1 point increase in ability score improves your ratio of successes to failures by about 41%. That means that two 1-point increases have the same combined effect as a single 2-point increase. That makes sense, doesn't it?