Characters can try just about anything. Just because you don’t have a specific skill written down on your character sheet, it doesn’t mean that you can’t give it a go. Describe what it is that you’re doing, and the GM will make a decision as to whether you’ve succeeded or not, taking into account the circumstances. Apart from situations where it is clearly inappropriate, player knowledge is just as important as character knowledge.
All things being equal, if no other circumstances apply, a character will normally succeed in a task if they roll a 1 or 2 on a d6. Some tasks, such as finding traps, or difficult situations like balancing on an icy tree branch, might require a 1 for success.
Some very tricky and/or time-consuming tasks might require more than one successful roll to achieve. Some may even require more than one simultaneous success roll, so only those characters who get more dice to roll would have any chance of succeeding!
Situations where a simple die roll might apply could be in climbing, balancing, sleight of hand, controlling a spooked horse, attempting to hide, trying to find a secret door you think is there — pretty much anything you can think of.
Your character wasn’t always a rugged adventurer, and their pre-adventuring background will provide a lot of guidance for both the player and the GM about what he or she is likely to know about.
Examples: an ex-farm-boy will have a lot of useful knowledge about handling animals, making and mending, the passage of the seasons and so on. An ex-apothecary’s assistant would be familiar with compounding ointments and other remedies, and would likely know something about herbs and their uses. A huntsman would know how to set snares, identify animal spoor, and butcher their kills.
It’s not necessary to develop a detailed back-story for the character, but just a little thought can ease matters later on.
Fighter and Thief characters are assumed to be illiterate, Fighter-mage and Magic-users are not. An illiterate character can learn to read during their career of course, or else they can use one of their “Good Ats” (see below) to be able to read. A literate character is assumed to be able to read and write in any language he or she knows.
Anybody can learn to pick locks, but the THIEF class is especially good at it.
A d6 is rolled twice:
Thief characters succeed on a roll of 1 or 2. For every three Thief levels, add another d6 to the second roll. In other words, at 3rd level the thief rolls 2d6 for success or failure, at 6th level 3d6, at 9th level 4d6 and so on.
Note that although the lockpicking attempt normally succeeds on a 1 (or a 1 or 2 for a Thief), particularly fiendish locks may require more than one success, or even be unpickable.
At character generation, every player may choose one thing for every full 5 points of Intelligence or Wisdom that they’re Good At for their character.
It’s incredibly simple. For instance, Hagar the Fighting Man is Good At Climbing. During play, a situation like this might arise:
DM: The horde of bugbears slowly advances, their wicked blades gleaming in the moonlight. With only the sheer cliff wall behind you, you fear that you are trapped.
Hagar: Can I scramble up that wall?
DM: Hmmm... It looks like a pretty tough climb.
Hagar: Well, my guy’s Good At Climbing.
DM: (Thinks for a moment) Okay, sure. You find some handholds that would have escaped the notice of an unskilled climber and are soon 15 feet above the heads of the howling bugbears.
After character creation, a player can gain more skills by finding a teacher and learning how to do things. In this fashion a character might gain an additional Good At, or they may even change an already existing Good At into a Really Good At. Which, of course, works like a normal Good At except that the player can now say “But Hagar is REALLY Good At climbing”. Skill training takes both time and money of course; the amount of both will depend on the individual skill involved.
There’s no particular reason why a “normal” character wouldn’t try the same thing, because the Good At doesn’t indicate a basic level of competency but rather an advanced skill. Thus a norm can still climb, just not as well.
If a d6 die roll is deemed appropriate, where a normal character would roll 1d6, a character who is Good At something would get an additional d6 to determine success. A character who is Really Good At it would get yet another.
The Good At skill can literally apply to anything the players come up with. Thief skills like Climbing, Picking Pockets, Lock Picking, Spotting Traps, etc are a natural fit, but so are things like Herbalism, Running Away, Working With Animals, Lying, Fast Talk, Horse Back Riding etc.