Captain Anorak's Guide to Gaming
Consistency: Stat Change over Time
Most RPGs handle stat change over time in a very unrealistic way. Most use experience points that allow uncontrolled stat growth. This prevents the game being consistent: player characters' stats can increase faster than those of normal people, and reach unrealistically high levels.

A more realistic system would include the following considerations:

1. A stat increases in response to the character gaining experience or training in that skill (experience points gained in calligraphy cannot be spent on combat skills).
2. A stat increases at a the same rate for PCs and NPCs (if an NPC takes ten years to reach a certain stat level, a similar PC should take a similar length of time).
3. A stat cannot go above a certain maximum level.
4. Someone with natural talent for an ability can learn that skill more quickly and reach a higher level.
5. A stat goes down with lack of practise.

A SIMPLE SYSTEM

Imagine a system with a stat called Combat Skill (CS). The average person has a CS of about 30; a street thug might have 40, a veteran soldier 50. Anyone with CS above 50 would be really hard - like a special forces soldier or similar action hero. The higher the level of skill, the greater the degree of natural ability and/or experience needed to reach that level, the greater the amount of training which is required to maintain that level, and the fewer people who have that natural ability and the opportunity and inclination to do the work necessary to reach that level. So, the higher the level of CS, the fewer people who can reach and maintain that level.

This is a simple system which describes the overall effect:

CS	Propotion of population having this level or more	Number hours of practise needed per month to keep in shape
30	90%	0
40	20%	2
50	5%	10
60	1%	20
70	0.2%	40
80	0.05%	100
90	0.01%	150

When you need to stat a character (PC or NPC), now what you do is ask yourself, 'Is this character in the top 0.01% of fighters in this society, or in the top 0.2%, or in the top 5%?', and you find the right level for the character, and stat him accordingly. Thus you might decide that the Emperor’s elite personal guards are in the top 0.01%, so they get CS 90, whereas a middle-aged infantry sergeant is simply in the top 5%, so he gets CS 50. This system also makes it clear how much time must be invested in training to keep a level up, which sorts out slackers.

RAW POTENTIAL AND TRAINING

The system described above goes much further than most games do in trying to quantify the levels of skill which people can achieve (ie. most games don’t even consdier it). But still it is weak: it does not separate out how many people could potentially achieve a certain level of skill, and how many actually do. To do this, we need a slightly more complex system.

Imagine a system where the current value of a skill is determined by multiplying a base stat by a training level. Combat Skill (CS) is based on a stat called Physique (Ph), so the level of a character’s CS is equal to the character’s Ph multiplied by his CS training level (CSTL). Now, people in this game-world have the following distribution of Ph levels:

Physique level	3	4	5	6	7	8	9
Proportion of people	0.01%	1%	30%	40%	30%	1%	0.01%

So the average person has a Ph of 6, and only 1% of people have Ph above 7.

The basic level of CSTL for this society is 5: everyone will get this except someone who’s had an unusually sheltered upbringing. To increase CSTL above this basic level, a certain amount of combat experience and/or training is needed.

CSTL	Total number hours practise needed to reach this level	Number hours of practise needed per month to keep this level
5	0 (basic level)	0
6	50	2
7	100	5
8	200	10
9	500	20
10	1000	50
11	2000	100
12	5000	150

To move from CSTL 5 to 6 requires a total of 50 hours. If a character gets one hour of fighting per week for a year, or gets 50 hours of fighting crammed into one month, in either case he will go up from CSTL 5 to 6. Once a character has logged a total of 5000 hours of combat or training in his life, he can claim the heady CSTL 12, which represents the height of achievable ability for this character. But to keep this level he needs to spend 150 hours a month in combat or training, or he will lose it and slip back down to CSTL 11.

What this means is that a character’s maximum ability is limited by the level of the base stat, Physique. A character with a Physique of 6 has a CS of 30 at the basic level of CSTL, and can never achieve a final CS higher than 72, even at the peak of his potential skill at CSTL 12. A character with Ph 7 will have a CS of 35 at basic level, and a maximum possible of 84. Someone with the maximum posible Physique of 9 will have a CS of 45 at basic level, and a possible maximum of 108.

A character with Ph 6 must reach CSTL 12 to get a CS of 72, whereas a character of Ph 9 only needs to reach CSTL 8 to achieve the same result. Thus, the higher a character’s basic potential (represented by Physique), the easier it is to reach a certain level of ability, and the higher the maximum level attainable, but ultimately the character is limited to a certain level of skill: it is impossible to keep on increasing skills indefinitely, as you can in most experience-point based systems.

Under the rules sytem outlined above, when statting a character, you ask yourself: ‘How much raw physical fighting ability does the character have?’ - and this supplies the value of Physique; ‘How much combat experience has this character had in the course of his life?’ - and this tells you the highest value which CSTL can have reached; ‘How much fighting experience does this character get in a month these days?’ - and this tells you whether or not the character will be at the maximum possible CSTL for the amount of experience he’s had. From these answers you work out Ph and CSTL, and you have a number for CS.