The PIP System is simple, but good. You need a number of six-sided dice of two colors; the rules will refer to white dice and black dice. Any colors will work as long as you designate which ones function as "white" or "black." You form a dice pool from the white dice based on your character's attributes (Body, Charm, Luck and Mind); one die in a stat is poor while five dice is awesome. As you roll your white dice pool, you simultaneously roll a number of black dice based on the difficulty of the task, with more black dice indicating greater difficulty. The player rolls both the characters white dice and the difficulty black dice. Each result of 4, 5 or 6 on any die is a success. Comparing the white dice successes to black dice successes, black difficulty dice cancel out white successes. If there are any white dice left, the character's action succeeds. The more dice remaining, the better (or worse) the task's results are.
For conflicts, when two characters face off, the attacker/acting character rolls her attribute dice (white) against the defender's attribute dice (black), per the rules above. The attacker determines what attribute she rolls based on the sort of conflict she's initiating, while the defender usually (though not always) defends with the same attribute:
Body: Hit you (attacking)/dodge you (defending) Charm: Persuade you (attacking)/assert will (defending) Mental: Trick or outsmart you (attacking or defending) Luck: Use magic (attacking)/resist magic (defending)
In the new edition, the system has Mental Health and Physical Health. Mental Health represents characters mood and level of mental exhaustion -- solving puzzles or being depressed can reduce a character's Mental Health while Physical Health represents damage done to a character's body.