City-State of Dire
On a successful attack roll, the defender suffers an amount of damage equal to weapon damage PLUS an amount of damage equal to the amount the attacker succeeded on his attack roll. A natural 20 on an attack roll counts as 20 plus another d20. The attack roll is continously rolled until it does not read 20.
Below Zero Hit Points
If an attack causes enough damage to drop a defender below 0 hit points the DM rolls a d10 and keeps the results secret. The result of this die roll is the amount of negative hit points the victim of the attack is negative. A result of 10 on this die results in immediate death, any other result means the victim is bleeding badly and will soon be dead. The victim loses one hit point each round, when he reaches -10 he dies.
If a character is at negative hit points he may still retain consciousness. Each round he must make a system shock, success allows him to stay on his feet another round. On a failed check the character immediately collapses into unconsciousness. Whether conscious or not, a character with negative hit points bleeds one hit point each round.