Hey there!
Im going to tell you a "harder" way to implement this and an "easier" way. Please be mindful if I say something that is impossible to achieve.
- The "hard" way.
Putting your controler/ingame hand on an npcs wrist or neck will send a slight vibration through your controler, accelerating and getting stronger the more the npc is damaged. This may vary.
- The "easier" way
Adding a steroscope or a heart monitor would make this process much easier, let me explain.
The steroscope: Putting it to an npcs chest sends a "thump-thump" heart beat sfx through your headset, accelerating as the npc takes damage.
"How would this effect the game?"
Amazing question!
Due to how the sandbox will be the main focus of the game, role-playing will be VERY popular, this would be a very useful feature for almost every roleplay and I strongly belive almost every roleplay would LOVE it!
I dont know if this is possible yet, if its not or is just too hard, just say it!