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..250]. Generally [0..100] for players
Rolls are open-ended 1d100.
It's a fair rule of thumb that a player's skill should roughly equal the player's level * 2. So a level 20 player should generally have a 40 swim skill (some more, some less).
Swim Skill
Let's use swim as an example. A characters proficiency in swim in 0..100. The table below is a rough translation of a swimming skill.
0: You'll risk drowning in shallow water where your feet touches the gound. 40: An average (real world) swimmer 100: is the best human swimmer in the (real) world. 200: is the most divine swimmer.
Now imaging 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.
A room's swim movement could be:
+50: The easiest possible circumstances. Shallow, clear, still water. Players with 0 skill fail half the time. . . 0: Average normal swimming conditions . . -100: The most absurdly difficult swim imaginable. It would mean the (real world's) best swimmer would fail half the time under these circumstances. 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.
flee
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.
search
Add notes on searching for hidden doors here