Provided link is to Wound Thresholds from Pathfinder Unchained as reprinted on Legacy.aonprd.com, for a reference point.
I run a Pathfinder 1e game set in Ustalav. In my campaign, we use a lot of variant rules. Among those rules are the Wound Thresholds rules from Pathfinder Unchained. These apply mechanical penalties as a character's hit points decrease. (Specifically, we use the Gritty Mode Wound Thresholds, which double the penalties.)
I introduced Gritty Mode Wound Thresholds at level 9 of the campaign on a trial basis, but the players seemed to like them so we've been running with them since. (They like them because I apply them equally to monsters as well, which means they can death-spiral monsters. I rule that anything immune to critical hits is also immune to wound thresholds, so incorporeals, oozes, and such.)
Background information about my campaign and my situation is behind a spoiler tag as it's extraneous information.
spoiler
Background: My Pathfinder 1e game, which started in 2012, has been on hiatus since December 2019, initially for our seasonal 3 month winter break, but then because Covid lockdowns started in March 2020, and finally because my family wanted to minimize exposure to other people so pressed me not to resume play right away. In May 2023 my family agreed it was reasonable that I take-up in-person play again. I had told my players I would give them a month's notice when the game was set to resolve again, so that meant gaming in June, but they weren't available, so that meant gaming in July. We scheduled for 29 July but since then all my players (except one that never responses to group messages) have canceled, with one being unavailable until June 2024, and the others (a couple) being indefinitely unavailable. I asked the couple if they wanted to drop out of the game permanently or still hoped to resume later, and the response I got back was that they hope to resume later. So I told them I would put the campaign back on long-term hiatus.
So there's no telling when or if we'll actually play again, but the campaign is not technically abandoned, as I specifically asked for clarity on that from the players.
I told my campaign players that I will seek to run some one-shots or smaller stuff while our campaign is on hiatus, so I can get my game fix.
So the meat of the situation is this:
We've been playing with Gritty Mode Wound Levels and I like them. I want to incorporate them into my games in the future. However, we started using them at level 9 in our campaign, when the players had high enough modifiers that it wasn't game breaking that they take some penalties. If I introduce them to a campaign at level 1 (and I also like to run at "level 0" (NPC classes) at the start of a campaign), I think they'll make the game far too hard.
So I'm considering scaling Wound Thresholds instead. Because Gritty Mode is -2 at every wound threshold, and there are three (75% or lower hp is -2 penalties, 50% or lower hp is -4 penalties, and 25% or lower hp is -6 penalties), I'm thinking I should introduce them gradually. But I don't want to surprise the players with them, so I want to write them into my table rules appropriately.
Basically, because the Gritty Mode is -2 at the first penalty, I think I should house-rule that the first penalty (Grazed, hp 75% or lower, -2 penalties) starts at level 4, the second penalty (Wounded, hp 50% or lower, -4 penalties) starts at level 6, and the third penalty (Critical at hp 25% or lower, -6 penalties) starts at level 8.
The Wound Thresholds system has a benefit as well, and that is that the Disabled condition isn't just at 0 hp, but at 0 hp to the negative of the CON modifier for characters that have a positive CON modifier. So a fighter with 16 CON is disabled at 0 hp to -3 hp, and only begins dying at -4 hp (but still dies at -16 hp). I would leave this benefit of the Wound Thresholds system intact from level 1 onward. (If we do "level 0," it would not apply at level 0.)
I have also buffed the Critical Cure feat to make it more effective, but it just now occurs to me that I need to recover my revised wording for that feat from a file format I can no longer easily access.
Anyone have any thoughts about this idea?
Besides the general consensus that "Wound Thresholds are terrible," I mean? I've heard that already.
I guess it's time for me to start compiling my Starfinder 1e shopping list. I have the Core Rulebook, but that's it.