On Survival Horror

I have been trying to figure out a system that is fair to use involving injury, near-death encounters, destruction of bases, infection, and other FUN THINGS that survival horror can do to your characters and the environment. I trust the story in player hands, which is why people get chances to GM their own events, but having a little chance thrown in the mix may add some fun.

If anyone has ANY suggestions for this please let me know. I've been thinking of using a super-simplified d20 system which would pretty much involve the GM calling for a roll on something, the player(s) rolling and the number would be interpreted by the GM within certain reason.

For example, something is attacking, GM calls for a roll, player rolls a five, the something does something according to that number. OR, in more complex situations, someone unskilled in first aid gives medical attention to another character including suture. Player of the unskilled character would possibly roll for mistakes, and injured character may have to roll for bodily fortitude to see whether or not the stitches get infected.