What do hit points represent?

[Valkyrie101]

AFAIK, Brothers in Arms: Hell's Highway did have this. It was in effect a regenerating health system, but instead of taking hits and then healing, being out in the open caused your screen to flash red and your "health" to go down, representing you being in danger and exposed to enemy fire. If your "health" reached zero, you took a hit and died.

 

[Zhukov]

So... how exactly does a first aid kit or its equivalent restore your "luck"?

At the end of the day, hit points, like many video game mechanics, are just a non-realistic representation of how things work in the real world.

 

[Wolfboy0311]

Your theory reminds me of Assassins Creed. You aren't ever dealt a serious blow, although portions of your health bar are depleted. Once you are dealt that serious blow it's usually a death sentence... or just restarting the simulation.
They're used in games to represent how much longer you have till you're dead or it's game over. Most of the time it's just there to measure how many more hits you can take.