Stealth is used whenever a character wants to do something without being noticed, or something that requires a combination of knowledge and dexterity. It is a combination of agility and intelligence.
Whenever someone might notice something sneaky going on, they make a perception check. Perception is a combination of intelligence and wisdom. As always, the highest total wins. So, if the thief rolls higher, then he continues on, unnoticed. However, if the observer rolls higher, he catches the thief in the act (and probably calls for the guard). Ties are awarded to the observer, although players may spend a karma point to win the contest, instead.
The environment plays a big role in the success or failure of stealth attempts. Anything that makes it more difficult to see or hear gives a bonus to stealth, and anything that makes it easier to see or hear gives a bonus to perception.
Very bright light: +4 bonus to perception rolls.
Very dim light: +4 bonus to stealth rolls.
Very quiet environment: +2 bonus to perception rolls.
Very noisy environment: +2 bonus to stealth rolls.
Activity/distractions in the environment: +2 bonus to stealth rolls
Looking directly at the thief: +10 bonus to perception rolls.
Tenpenny Nails is a local cutpurse who is well known by the city guards and merchants alike. Tenpenny has his eye on a merchant’s safebox in the city square, and has decided that he’s going to try to snatch it right as the market closes for the evening. The DM decides that the noisy environment is counterbalanced by the fact that the merchant is closely paying attention to his safebox, and so determines that there are no modifiers to either roll.
Tenpenny has an agility of 60, and an intelligence of 45. His stealth roll is (2d8) + (2d6). The merchant has an intelligence of 60 and a wisdom of 75, so his perception roll is (2d8) + (2d8). Tenpenny rolls a 24, and the merchant rolls a 20. Tenpenny carefully scoops up the safebox while the merchant is distracted, and turns to hurry away with his prize…only to run straight into the hands of the local guard who happened to roll a 30. The safebox is returned to the merchant, and Tenpenny will spend the next few days in jail.