Manual:Game Mechanics/Skills

It seems skill (spells et. al) checks got kind of lost in the mists of time. Here is the general idea:

Skills and abilities are all in [0..200] Rolls are open-ended 1d100.

Let's use swim as an example.

A characters proficiency in swim in 0..200.

  0: Zero means no skill at all
 75: An average swimmer
200: is the most divine swimmer.

Now image having swim in average conditions. If your skill is average (50) then the skill check is to see the result of (1d100 + skill) - 100. If the result is above 0 the swim was a success. Therefore if your skill is 0 you always fail an average swim roll is > 100. If your skill is 75 for an average swim, you succeed 75% of the time. If your skill is 100 then you always succeed. Remeber that the open-ended roll can of course always offset even a sure success or fail.

The difficulty of a swim could be:

 +50: The easiest possible circumstances. Shallow, clear, still water. Players with 0 skill fail half the time.
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   0: Average normal swimming conditions
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-100: The most absurdly difficult swim imaginable. Players with 200 skill succeed always (except OE).

A character that fails a skill check might be swallowing water if the fail is [0..-20]. And might take one hp damage per 10 failure if the result is worse than -20.

The function skillcheck() captures precisely this setup.

For a skill like flee, the difficulty could be an expression of the character's and opponent levels compared.

 +5: For each level better than the opponent
  0: Same level, no modifier
 -5; For each level worse than the opponent

So a level 5 PC fighting a level 1 rabbit gets a +40 bonus to flee. Since an NPC does not have skills, generally its level can be used as its skill. So a level 50 NPC has a flee skill of 50.