Whilst the (optional) wound tracker is a departure from standard 5e, it’s done in a way that slots into the existing rules with very little extra adjustment. It’s effectively a new condition, working in the same cumulative way exhaustion does. But Importantly the levelling and Hit-point progression remains inline with 5e (which is what I meant by structure of level progression). The recommended play is only going to 10th level. There are options for progressing beyond that if you wish.This is an example where the structure of level progression changes. (And yes, I agree this is likely much more invasive measures than what XOth intends with the product of this particular thread).
As an optional condition the wound tracker is very easy for players who don’t want to use it to ignore, but it does help to shape the character of the different setting.
Games like Trudvang 5e, Beowulf, and AIME, are really good examples of how you can you turn 5e into a genre appropriate game, but still keep the basic 5e expectations IMO.
To be clear I’m not saying the Trudvang wound tracker is necessarily appropriate for this game. Though it does a good job of modelling combat fatigue (without graphic limb loss, and permanent injuries).