Stopwatch HP, no HP

Josie mentioned treating HP like a stopwatch. We played around with this for a while and here's what's been extruded through our game and come out the other end:

NO HIT POINTS
Get rid of hit points. No hit points, "endurance points." Fending off attacks, hurting yourself in a non-debilitating way (bruises, bumps, scrapes, cuts that aren't going to kill you) and particularly strenuous or taxing actions cost endurance points. Endurance points represent your energy level and, accordingly, your capacity to forestall some immediate, debilitating danger; when someone lands a successful attack, the loss of endurance points represents how much it costs you to fend off the attack and prevent it from doing serious damage and being reduced to 0 EP means you're too drained to do anything. Losing EP is being "worn down."

SO... SAVING THROWS
Catastrophes and calamities (ingesting lethal poison, falling ceilings, being stepped on by a giant) are systemic traumas you can't avert with endurance or force of will. Saves cover this. Save as normal or here. Generally, save or die, earn a wound or suffer an enormous reduction in EP.

0 ENDURANCE POINTS
Being reduced to zero endurance means that you are exhausted, can barely move, lift a sword, everything feels like it costs a ton to do it. There's no "extra exhausted," so no negatives. When you're at 0 EP, anything that would otherwise result in a loss of endurance points but isn't the result of a deliberate effort to kill you (like, falling) automatically causes a wound. If the attacker is trying to kill you, save v death or die; a successful save earns you a wound. If an attacker is trying to knock you out, save v paralysis or get knocked out; a successful save earns you a wound.

BEING WORN DOWN, ESCALATION
Being encumbered, swimming in medium or heavier armour, running in armour with a heavy pack for more than a few minutes, holding your breath too long, being in combat or any other highly stressful, dangerous, tiring situation wears you down.

Each go round the table (in whatever time metric the GM deems appropriate, given the current action), everyone being worn down loses an EP.

WOUNDS, RESTING AND HEALING
If you can spend a round catching your breath without having to do anything else (including patching up an ally), your EP increases up to half its maximum. So like, you flee combat with a couple of ogres; if someone has to hold the door against the ogres, then they don't regain any EP but if you spike the door, then everyone can get EP back.

Resting for a turn restores all EP.

Wounded characters must be treated before they can regain EP and their max EP is halved until they can get some bed rest and serious medical attention (likely takes a few days or weeks, depending on the wound) or sufficient magical healing. A second wound is automatically fatal (no save).