Small Arms: head
My friend Jeff and I played the original 2k all of '85 and the first half of '86. In a single campaign, we'd logged 36 PC deaths between 4 players. Most popular cause of death being Small Arms fire to the head. It got so lethal, that we would play 2 characters at a time, just so we wouldn't be out of luck if one of our characters bought the agricultural real-estate.
Only 2 characters survived the whole campaign to get home. my character Francis X. O'Hallaran, a photojournalist and some time spy, and Poco Pie, my friend Lance's whacked-out Ranger. God I miss that campaign... Good times, Good times.
d20 Modern rule base would be fine by me. I'd like to pick it up without having to pick up $3x10^5 in sourcebooks.
As a side note, we adapted the 1st ediiton T:2k rules for Battletech and it really worked out. The 1st edition rules were simple once you learned got past the Character Generation Worksheet.