First Aid

 

First aid is a mod available in 1.12.2 , 1.14. , 1.15 and 1.16!
It completely changes the old health system with locacalized hearts!
Meaning if you take get shot by an arrow in the leg and it loses all of it's hearts it will broken and you will get a slowness debuff until you heal it!
With this change, armour has changed as well as it now provides a localized armour!
Providing a better combat realism and difficulty into the game!
It's also can be seen used in RLCraft!

As you can in the picture I have provided above each part of your body has it's own set of hearts,
with the head and body having hardcore hearts meaning that if you get a deadly shot in either of them, one shot kill!

This icon will appear ingame.
It represents the status of your health.
Green: Non damage taken
Yellow: Minor damage
Red: Broken

This mod by default disables natural regeneration, so you can no longer start a world and go on a killing rampage with no armour on because you will probably get one shot by a skeleton or die due to a creeper sneaking up behind you...

Mod owner is: ichttt. 
First aid is one of the coolest mods so far as it brings hardcore to survival!
So if you feel like Minecraft's too easy give it a try!