Here are some I am working out for an upcoming campaign:
Action Points as per D20 Modern
Alignment: Detect Evil, Good, Chaos, etc. Living creatures receive a saving throw to negate. DC of 10 + the level of the spell - Will of a potential target in range.
Armor bonus as Damage Reduction not AC bonus.
Defense Bonus for classes as per D20 Modern counterparts Strong Hero = Fighter and see below.
The two above are counteracted with lower availability of metal armors and the extreme scarsity of magical armaments above +1
Critical Threat automatically cause Critical Hits.
Massive Damage: When a creature or character suffers damage in a single round (not a single attack) higher than an ability score, up to three Saves may need to be made.
If damage > higher of Dexterity or Strength then Reflex Save vs DC=damage) the character is Knocked Down/Prone and Stunned 1d4 rounds.
Stunned: A stunned creature drops everything held, can’t take actions, takes a –2 penalty to AC, and loses his Dexterity bonus to AC (if any)
.Knocked Down/Prone: The character is on the ground. An attacker who is prone has a –4 penalty on melee attack rolls and cannot use a ranged weapon (except for a crossbow). A defender who is prone gains a +4 bonus to Armor Class against ranged attacks, but takes a –4 penalty to AC against melee attacks.
Standing up is a move-equivalent action that provokes an attack of opportunity.
If damage > higher of Intelligence of Wisdom then Willpower Save vs DC=damage) the character is Unconcious 1d4 rounds.
Unconscious: Knocked out and helpless.
Helpless: A helpless character is paralyzed, held, bound, sleeping, unconscious, or otherwise completely at an opponent’s mercy. A helpless target is treated as having a Dexterity of 0 (–5 modifier). Melee attacks against a helpless target get a +4 bonus (equivalent to attacking a prone target). Ranged attacks gets no special bonus against helpless targets. Rogues can sneak attack helpless targets.
As a full-round action, an enemy can use a melee weapon to deliver a coup de grace to a helpless foe. An enemy can also use a bow or crossbow, provided he is adjacent to the target. The attacker automatically hits and scores a critical hit. (A rogue also gets her sneak attack damage bonus against a helpless foe when delivering a coup de grace.) If the defender survives, he must make a Fortitude save (DC 10 + damage dealt) or die.
Delivering a coup de grace provokes attacks of opportunity.
If damage > Constitution then Fortitude Save vs DC=damage then the character is reduced to 0 hp but is stable.
Below 0 hit points: Treat character as Disabled.
Disabled: A character with 0 hit points, or one who has negative hit points but has become stable and conscious, is disabled. A disabled character may take a single move action or standard action each round (but not both, nor can she take full-round actions). She moves at half speed. Taking move actions doesn’t risk further injury, but performing any standard action (or any other action the DM deems strenuous, including some free actions such as casting a quickened spell) deals 1 point of damage after the completion of the act. Unless the action increased the disabled character’s hit points, she is now in negative hit points and dying. A disabled character with negative hit points recovers hit points naturally if she is being helped. Otherwise, each day she has a 10% chance to start recovering hit points naturally (starting with that day); otherwise, she loses 1 hit point per day. Once an unaided character starts recovering hit points naturally, she is no longer in danger of losing hit points (even if her current hit points are negative).
Below –10 hit points: Dead.
Healing is accelerated: Class Hit Die x Level per day.
Experience Points: In general xp will be given out generously, especially for what I consider “in-character” actions based on your character’s background, race, class, etc. Excessive metagaming is discouraged and may be penalized.
Hit point accumulate at the higher of the average (1/2 max) and a roll. Take the higher (i.e. a Fighter will get between 5 and 10 hit points each level)
A character may take no more than 1 prestige class and one second class in addition to his or her starting class. Racial levels do not count toward this limit.
Cleric: Defense Bonus of the Dedicated Hero or the Smart Hero. If taking the Defense Bonus of the Smart Hero, the character is only proficient with light armor but also gains additional spells per day as per the Priest class spell progression.
Fighter: Defense Bonus as per the Strong Hero or the Quick Hero. If taking the Defense Bonus progression of the Quick Hero, the character is only proficient with light armor and shields.
Sorcerer: Requires no material components for spells. The Sorcerer may instantaneously cast any spell she know which she has a remaining slot. Sorcerer may attempt to learn new spells from scrolls or from studying a spellbook of some other spell caster as long as the spell is on the sorcerer’s spell lists.
Wizard: May forgo material components in exchange for damage to Constitution of one point per level of the spell cast divided by ½ her level, round up. The Wizard has spell slots as per the Magister in Arcana Unearthed.