These house rules should make combat somewhat less deadly, while at the same time increasing the probability for heroic success and catastrophic failure.
Crits: On a roll of a natural 20 the attacker makes maximum damage plus an ordinary damage roll!
Fumbles: On a roll of a natural 1 the combatant suffers bad luck or makes a terrible mistake, he or she may loose the next turn or the opponent may get a bonus on the attack roll.
Damage: Hit Points is an abstract measure of the PC’s endurance, loss of HP represents fatigue. At zero HP the PC is tired and starts taking real damage. Every time the PC suffers damage after that all the HP have been lost the player must make a saving throw. Failure means that the PC has suffered a fatal wound and dies, success means that the PC survives but is wounded. For each wound there is a cumulative negative modifier to all rolls, including saving throws.
Regaining HP and healing wounds: If a PC that has suffered loss of HP can find uninterrupted rest for one hour 1d4 HP is recovered. A whole nights sleep restores all lost HP. Wounds heal at a rate of one per week of uninterrupted rest. Wounds that are left untreated after a combat may lead to further saving throws, failure result in additional wounds due to infections.
XP: If the players are able to overcome or circumvent a hostile creature by wits or negotiation instead of violence they gain the same experience points as if the foes had been defeated in combat.