I don't like HP for a number of reasons, and I'd like to replace it with something better. Abstracted as 'hit points' it could mean almost anything, but most people tend to read it as 'health' or 'life,' which makes turn-based battles feel like everyone is standing in place, just hacking away at each others abdomens until one of them finally drops. But that's not really how fights work, and it leaves you with what I think is a pretty weak conceptual and mechanical foundation to combat.
|Fatigue, by Magnus Fallgren|
The first change is pretty simple, just call it Guard instead, with successful melee attacks wearing away at your guard until you become vulnerable. Another successful attack beyond that will cause a Wound that leaves the target incapable of combat. It could be anywhere in a wide range of severity, but personally I'd recommend making the player the one who ultimately decides if their character will die. I'm also a big fan of downtime, taking a break to really heal so that the game doesn't feel like an insane rush where an entire world-saving campaign happens in a week or two. To this end I like a week to a month as the healing time for most Wounds.
(I also like a week of downtime required for leveling up, but that's probably even more controvertible)
Characters also have Endurance, which they can spend a turn using to restore their Guard. Endurance would also be what most non-melee threats deplete, since you don't exactly block or parry arrows or a rolling boulder. You could have Endurance recover after a night's sleep, but a full day off makes more sense to me. Most people don't feel fully recovered until they spend a day relaxing, after all.
|Day 21: Furious Undead, by Konstantin Vavilov|
There might be a mental analogue to Guard, such as Focus for spellcasters and potentially archers or other ranged attackers, refreshed in a similar way by expending Endurance. To add some extra spice and realism to melee combat, characters can also make a Finishing Strike or Aggressive Attack where you roll a larger damage die, instantly Wounding the target only if it rolls higher than their current Guard. It does nothing if it rolls lower though, and might cost Endurance to attempt.