I use d6 group initiative. One player rolls a d6 and I roll a d6. If they meet or beat the bad guy's roll then the party members all act first. The actual numbers rolled don't matter. "Bad guys 3, Players 6" has the exact same mechanical effect as "Bad guys 2, Players 3". What if that wasn't the case? What if the number rolled indicated how much you could get done before the end of the round? Below is a stab at the idea. I don't usually like new mechanics that require you to consult a new chart all the time, so I'm not sure I'd use it as a hard and fast rule. But I think I will start considering the number on the inish die as a means of gauging how much the PCs can achieve in a round.
Players' Roll
1
Cast 1st level spells safely
Wielders of two-handed weapons may not attack this round.
Only weapons in hand may be used to attack.
Scrolls/potions/wands/oil may only be used if in hand and ready for use.
Missile fire into melees targets randomly.
2
Cast 1st and 2nd level spells safely
Wielders of two-handed weapons may only make unarmed attacks, weapon out of position.
Scrolls/potions/wands/oil may only be used if in hand and ready for use.
Swords and daggers may be drawn and used immediately.
3
Cast 1st-3rd level spells safely
Scrolls/potions/wands/oil may only be used if in hand and ready for use.
Swords and daggers may be drawn and used immediately.
4
Cast 1st-4th level spells safely
Swords and daggers may be drawn and used immediately.
Fighter types who drop their foe may make an extra attack.
5
Cast 1st-5th level spells safely
Any melee weapon may be drawn and used immediately.
Anyone who drops their foe may make an extra attack.
Missile fire may fire at small targets (a sword hand, the wizard's magic eyeball, etc)
Hand held weapons may be thrown and a new weapon drawn for use next round.
6
Cast any spell safely
Missile fire may fire at small targets (a sword hand, the wizard's magic eyeball, etc)
Crossbow users may fire and immediately reload (but not fire at small targets)
Any melee weapon may be drawn and used immediately.
Hand held weapons may be thrown and a new weapon drawn for use next round.
Anyone holding a dagger may make two melee attacks.
Anyone with a shield may make an extra shield bash attack.
Anyone who drops their foe may make an extra attack.
Monsters' Roll (humanlike foes use the above chart)
1
Claw/Claw/Bite Types: one claw only
Tentacled Horrors: one tentacle attack only
Monsters that Swallow Hole: bite but no swallow possible
Breath Weapon: no breath weapon allowed
Gaze Attack: no gaze allowed
General: Only front line party members can be meleed
2
Claw/Claw/Bite Types: both claws
Tentacled Horrors: d6 tentacle attacks
Monsters that Swallow Hole: as normal
Breath Weapon: small puff targets 1 foe for half damage, does not count as a usage per day
Gaze Attack: gaze attack 1 target
General: Only front line party members can be meleed
3
Claw/Claw/Bite Types: both claws
Tentacled Horrors: d6 tentacle attacks
Monsters that Swallow Hole: as normal
Breath Weapon: full breath weapon
Gaze Attack: gaze attack 1 target
General: Only front line party members can be meleed
4
Claw/Claw/Bite Types: full attacks
Tentacled Horrors: d6 tentacle attacks
Monsters that Swallow Hole: as normal
Breath Weapon: full breath weapon
Gaze Attack: gaze attacks d6 party members
General: Party members behind front line can be targeted in melee, but front line makes rear attacks
5
Claw/Claw/Bite Types: full attacks
Tentacled Horrors: d6 tentacle attacks
Monsters that Swallow Hole: as normal
Breath Weapon: full breath weapon
Gaze Attack: gaze attacks d6 party members
General: Party members behind front line can be targeted in melee, but front line makes rear attacks
6
Claw/Claw/Bite Types: full attacks plus some bonus (grab, tailslap, headbutt, etc)
Tentacled Horrors: all tentacles attack
Monsters that Swallow Hole: bit/swallow up to d4 adjacent targets
Breath Weapon: full breath weapon
Gaze Attack: gaze attacks all possible targets
General: Party members behind front line can be targeted in melee