Although I've talked about this before, recent comments at a couple well respected blogs have lead me to believe I should bring it up again.
One thing about hit points is they are vague, while luck points are not. A hit point is either physical damage or stamina or fate or training or morale, and the problem comes when they are merged and two parties have disagreements over how it should. Luck points create a clear distinction which allows for many new gaming opportunities.
Because a luck point is explicitly luck it allows for (should you wish it), transferability. In my experience this is the favoured trait among players. Luck points can be transferred downstream and end a lot of bad RPG tropes. When I say downstream I mean that a knight could use his luck points to keep his horse alive (instead of mounted combat lasting exactly 1 round at higher levels), but a squire could not use his luck points to keep the knight alive. This becomes exceedingly useful in naval games as well, where the 10th level PC captain is actually better in ship to ship combat than a 1st level PC captain thanks to luck points.
This leads me to point 2, scalability. Because the captain would have no rule benefits if his luck points didn't scale to deal with cannon fire, so if a cannon does "4 hull damage" or what have you, then the Captain can use 4 luck points to have the shot "narrowly miss" the ship or fail to cause any real damage, just as he could use 4 luck points to avoid a well placed dagger thrust on himself personally.
This then deals with the ability to By-Pass luck points. Now bypassing should be a rare and not in any way random event. The most common way to bypass is to simply burn through all of the luck points and deal physical damage. But certain rare elements (say a Destiny point in piecemeal, though perhaps something like a prophecy or magic spell in your game if you used the mechanic) do allow it, as does willful player choice. A player who tackles a figure in the darkness and finds out its a man in spiked armour takes luck damage, a player who chooses to tackle a man plainly wearing spiked armour after being warned, would bypass luck points.
Once you are through the luck points you can use whichever system you like, a death and dismemberment table, a simple "1 hit and you are dead", in my case I use "Body Points" to represent physical damage, this allows for a downward spiral as taking damage gives you universal penalties. It also means luck can heal in a few days but physical damage can take months. For example in my current game there is a dwarf who has healed to 24 luck points, but has taken so much body damage that he is at -5 to all die rolls (Attack, damage, etc) he makes.
Why is all of this better than HP:
Its explicit what luck points are
It ends a lot of RPG tropes (killing the horse, HP > 0 = ready to rock, Ships = Shipwreck misspelled).
It allows new options (transferring luck, deciding between lost luck and body point, etc)
Warrior of the Steppes
5 hours ago