Brainstorming: Split initiatives/Shorter rounds = dynamic combat?

[Saintheart]

Couple of small notations, and I wish I was wearing something other than the black hat right now:

(1) For PbP games (and only PbP as opposed to Roll20 or FtF), this would blow out combat resolution times more or less by definition since it necessarily asks everyone to post at least twice per round rather than once ... and it takes long enough to finish a single round of combat in PbP as it is.

(2) Notice that under this system a round's complexity grows pretty substantially the more combatants you've got in it. The initial example has three Named Characters and two cronies. Those cronies bite the dust in less than one round. If the cronies had been instructed to do something more complicated - specifically, Readied Actions on mages or other characters - then it starts to get complicated.

(3) Mages with high Initiative and a preference for direct damage line/cone/burst effect spells get borked hard by this system since if they have to go first, they have to basically call their shots on the target and give it a chance to react first to get out of the way of the casting before it lands, and then counter the enemy's assault. Indeed metagaming becomes a larger concern here since players will know the spell being cast while their characters won't. That isn't really something that happens in orthodox D&D combat because the spell lands at about the same time as it's first declared you're casting it. Yes, you could impose a Counterspell-ish mechanic to keep this tendency down to a minimum, but the main problem is that even if you don't know what spell is being cast, you know something's being cast - in a sense it turns all spells into what they'd be as full-round actions, i.e. notified to the opponent and giving him a chance to prepare contingencies for it arriving.

(EDIT: (3a) - I wonder whether this sort of mechanic, though - taking your turn in half-turns, thus giving you more time to react - could work as an alternative to a Rogue's Evasion feature, since it's meant to be fluffed as preternatural quickness or a sort of sixth sense that means they don't take damage from spells as much as others do?)

(4) I have a feeling that, oddly enough, people with low Initiative actually prosper under this system for similar reasons - this is basically forcing an opponent to give his enemy an idea of what he's doing before the consequence of that result hits him. I don't know if that's wrong or right, that's just the general observation on this system.

(5) Swift Actions and Immediate Actions in particular need separate consideration, since Immediate Actions in particular allow a person to respond to another character's action before it's completed. There are large swathes of ToB maneuvers -- counters -- that are devoted to this sort of thing. A person can take a swift action once per round in addition to standard plus move action (and in the case of the Ruby Knight Windicator, several if the DM is generous with Divine Impetus.) Or indeed consider how the Belt of Battle - a common must-have for characters of all types because it grants more actions per round - functions. Does the person have to split their bonus actions between the two halves of the round, or what?

(6) Also consider how Rapid Spell or Quicken Spell function in this system too. My guess would be that Quicken Spell -- which renders a spell a free action -- becomes even more powerful than it already was since it takes out any possibility for a spell's target to deploy countermeasures or prepare for the spell coming in.

(7) What would action-affecting spells such as Incite, Inhibit, and Slow do under this system? Slow would have to be adjudicated carefully since it allows either a move or a standard action but not both. Under this system that would probably hobble people more than they already are. Inhibit probably acts as it already does, but does Incite force you to take your standard action and move action at once, no second half-turn?

Again, I wish I was wearing something other than the black hat. 3.5's initiative system is just eye-gougingly terrible to implement in PbP, and I've sometimes toyed with the prospect of trying to come up with something different, but I have failed. This will I think make FtF D&D combat a bit more interesting and capable of strategising, but it does also alter how different classes will approach combat generally.