The PDQ (Prose Descriptive Qualities) system is a rules-light game engine that has three different levels of task resolution for any situation, in order to let players resolve encounters in as much or as little detail as desired.
The mechanism is to generate a random number or roll, add a freeform stat or set of stats, and compare to a difficulty number — either a fixed difficulty number or the opponent's roll. In conflicts, the amount which you beat another character's roll by is the amount of damage or failure ranks (see below). Stats are rated in five named ranks: Poor [-2], Average [+0], Good [+2], Expert [+4], and Master [+6].
Conflicts result in the accumulation of either "failure ranks" (which recover at the end of the contest) or "damage ranks" (which may take longer to heal). Each point of either type means that the loser must choose a stat to downgrade by one rank. So if you lose a conflict roll by 3, you must lower three stats each by one rank, or one stat by three ranks (with a minimum of Poor: -2). You can choose any stat to take your damage in — i.e. you can downgrade your "Accounting" quality based on a hit in a fight. When you can't lower your stats any lower (i.e. a hit when all stats are at Poor [-2]), then you have lost the contest.