the combat mechanics of rolling Weapon Dice, adding personal adds, and totalling each side of a melee, then comparing both sides. The lower side takes the difference as damage, spread evenly, then each share reduced by that character's armor, and marked against Constitution.
the Saving Roll system of 2d6 "DARO" (Doubles add & roll over, a form of open ending) for a Target number reduced by an attribute. Some expressions add the attribute to the die roll rather than subtracting if from the target number.
Attributes are rolled on 3d6 each, and often multiplied by racial modifiers.