The HD system (HDs for short, pronounced “heads”) is a system for use in role-playing games. It follows suit of the classical style, otherwise known as old-school, but might find application in trad, narrative or lyric style of game play with enough curiosity. The basic framework of the HD system is the fluctuation of the Hit Dice, a general measure of the capability of a character. This measure can go up or down many times within a given campaign, session, or scenario.
The HD system can be supplemented with mechanics for any number of stats or abilities. The straightforward resolution being roll 2d6 added to an ability number over a result of 20 to pass, but this can be swapped with the dice of your choice or all together replaced or removed. It doesn’t really matter all that much.
Rules (combat, social, downtime, fishing, marriage, divorce, etc) can be peppered in. Play to taste.