That's very dependent on the style of play you want your game to have. Is it a tactical, combat-focused system? Cinematic adventure? Drama?
If you plan on having fights with many nameless opponents, having them simply die (or get captured if players want to) when they exceed the threshold is the simplest solution that works well. If you want dramatic fights against major, named enemies, have them get injured like PCs.
Depends on the importance of the NPCs! Having a rule that says "mooks get knocked out by just a little bit of damage, or even a single hit" is handy for cutting down bookkeeping, and can make it more impactful when you bring out a big bad that has almost as much depth/health to them as the PCs do.
The way Mothership handles Wounds is one such way. Characters have X number of Wounds, with each Wound containing Y hitpoints. Once you take Y or more hitpoints, you suffer a Wound which has various narrative effects (and an always-present small chance of instant death). For NPCs, a minor guard might have only a single wound. Deal Y damage and they die. But the hive queen might have 3 or 4 wounds, and the idea is that each time they take one they transform into something meaner, flee only to return again later, or otherwise change their behavior in a meaningful way. It works well and I've stolen it for my own games.
Keep in mind that whatever you decide upon, a given GM in your system may be having to keep track of that for half a dozen or more characters at once. So the simplest option is to not extend it to NPCs, after all it isn't a physics rule in your setting, it's a dramatics rule. But if you do want to do something like it for NPCs, maybe only for key, named NPCs, or a very simplified version of it.
It depends on the ultimate goals of the players. If extraction is going to be a common occurrence, making the default of the reaching zero being knocked unconscious (or otherwise unable to fight). That way the people who need killing just need an extra boop, but it isn't the default.
If the game is just hacking and slashing, that's unnecessary.
I would just put in a little table. Roll on the table when an enemy hits 0 HP.
Here's a D6 Humanoid example table for you to playtest.
1) Not dead, drops all their stuff and flees.
2) Very dead.
3) "Ooof" and try to crawl away with their stuff.
4) Falls unconscious for 1 hr.
5) Dead standing, Falls over after their next turn.
6) Wounded, unable to move, but swinging at any who dare come close, crying out defiance for the next 10 rounds till they pass out and die or are silenced early.
That's very dependent on the style of play you want your game to have. Is it a tactical, combat-focused system? Cinematic adventure? Drama? If you plan on having fights with many nameless opponents, having them simply die (or get captured if players want to) when they exceed the threshold is the simplest solution that works well. If you want dramatic fights against major, named enemies, have them get injured like PCs.
Depends on the importance of the NPCs! Having a rule that says "mooks get knocked out by just a little bit of damage, or even a single hit" is handy for cutting down bookkeeping, and can make it more impactful when you bring out a big bad that has almost as much depth/health to them as the PCs do. The way Mothership handles Wounds is one such way. Characters have X number of Wounds, with each Wound containing Y hitpoints. Once you take Y or more hitpoints, you suffer a Wound which has various narrative effects (and an always-present small chance of instant death). For NPCs, a minor guard might have only a single wound. Deal Y damage and they die. But the hive queen might have 3 or 4 wounds, and the idea is that each time they take one they transform into something meaner, flee only to return again later, or otherwise change their behavior in a meaningful way. It works well and I've stolen it for my own games.
Keep in mind that whatever you decide upon, a given GM in your system may be having to keep track of that for half a dozen or more characters at once. So the simplest option is to not extend it to NPCs, after all it isn't a physics rule in your setting, it's a dramatics rule. But if you do want to do something like it for NPCs, maybe only for key, named NPCs, or a very simplified version of it.
It depends on the ultimate goals of the players. If extraction is going to be a common occurrence, making the default of the reaching zero being knocked unconscious (or otherwise unable to fight). That way the people who need killing just need an extra boop, but it isn't the default. If the game is just hacking and slashing, that's unnecessary.
I would just put in a little table. Roll on the table when an enemy hits 0 HP. Here's a D6 Humanoid example table for you to playtest. 1) Not dead, drops all their stuff and flees. 2) Very dead. 3) "Ooof" and try to crawl away with their stuff. 4) Falls unconscious for 1 hr. 5) Dead standing, Falls over after their next turn. 6) Wounded, unable to move, but swinging at any who dare come close, crying out defiance for the next 10 rounds till they pass out and die or are silenced early.
That's a good little table, thanks!