My friend and co-tinkerer, Jon from Seattle (aka Redbeard), has released a revised version of his Castles and Crusades variant combat rules based on feedback from many of you fine folks. I'm pasting his latest greatest below (for more discussion about it, mosey over to Dragonsfoot here.)
Why a Grid? To enjoy combat as a tactical mini-game. Tumbling, flanking, pulling an Errol Flynn. To give the melee types the ability to protect the squishies, define simple “Attacks of Opportunity.”
1.Defining the Grid: Go with 5' squares and round to nearest.
2.Threat Range aka Reach
*Threat Range is how far you can reach and smack someone with a melee weapon if you've got one (or if you're trained in unarmed combat) and you're currently able to defend yourself.
*Most melee weapons for human sized critters will have a threat range of 5' – one square
*Polearms have a threat range of 10' if you've been trained with them (see Class Abilities).
*Weapons like nets, whips and chains may have larger threat ranges.
*Larger creatures will have larger threat ranges. Add 5' for each size greater than medium.
*Extraordinarily small creatures, such as Pixies, may have no Threat Range at all.
*Some creatures like snakes or creatures with long appendages may have Threat Ranges larger than their size would indicate.
*You get to make a Threat Attack on an enemy when it first enters your threat range. The Threat Attack is resolved immediately, before the enemy gets to make another action.
*Most combatants only get to make one Threat Attack per round.
*The CK can allow Threat Attacks when an enemy is unable to defend itself. Beg your CK.
*Aware combatants are assumed to be able to adjust their facing as needed during a round (as usual, the CK applies commonsense to this rule. This is to keep people from simply running around behind someone who sees them coming.)
*Flanking: When two (or more) attackers are on completely opposite sides of a target, all such attackers are considered Flanking and get +2 to hit. Rogues qualify for backstab.
5.New Combat Maneuvers for the Grid Push: A successful Push pushes the target back 5' in the direction desired by the attacker, who moves into the vacated space. The target number is 10 plus the to-hit bonus and size of the defender (+2/-2 per size difference). The attacker rolls a d20, adds strength and base to hit for combat trained classes (CK's discretion.) An attacker using a shield adds a +2 to the die roll.
Body Blow: a big hit (19 or 20 on a successful to hit) from a melee attack (determined by CK) can push a target back 5' and enter the vacated space. Defender gets a strength saving throw against 10+damage inflicted with -2/+2 for each size difference.
Tumble: Avoid a threat attack by making a Tumble check (dex check, + character level for rogue, assassin, monk). The target number is 10+ the base to hit of the Threat Attacker.
Dodge: a defender can increase their dodge bonus against one attacker from +2 to +4 by giving ground and moving 5' back in the direction specified by the attacker.
6.Class Abilities (which class gets them) Hold the Line (Fighter): When a character with the Hold the Line ability succeeds on a threat attack, the target must cease movement in that space.
Combat Reflexes (any character with strength prime): A character with Combat Reflexes may make one Threat Attack per opponent entering Threat Range, not one per turn.
Potent Charge (Fighter, Knight with Lance) - if the character with Potent Charge is being Threat Attacked by the target of a charge, the charge is resolved first if the charger's weapon can reach its target (instead of the threat attack being resolved first.)
Uncanny Dodge (Barbarian,Monk) Can't be flanked except by attackers of higher level.