Germ of an idea for dynamic HP economy in a dnd-like game
Regular readers will remember that in my work-in-progress fantasy heartbreaker Coup Étrange, "HP" stands for "hero points" which are supposed to be spent throughout play. (Actual design is notably lacking on this subject.) Meanwhile real wounds, with game-affecting consequences, belong to a separate subsystem, which is usually only engaged when the character is hit by an attack and they are out of HP. Readers may also recall my suggestions (I don't remember where I put this actually) that some kind of barbarian or berserk warrior could get +1HP/HD killed, keeping the rage machine fueled. So the idea is, you start every scenario with a random amount of HP, in a range fixed by your level and class; say, Xd6+1 for a level X fighting-man. You can increase your current HP past your starting HP, all the way up to, say, 6*X+1 for that same fighting-man. Meanwhile you're also going to be spending it to avoid damage and do cool shit in combat (design work needed here...