I have come up with a way to merge an AP based combat system like Azhanti High Lighting and 'interrupts' as in MegaTraveller combat. This will give a nice flow to combat sessions without resorting to very short turn lengths ( SPI's AirWar ) or master phasing count tables ( CarWars, Advanced Small Arms Spectrum, or Sword's Path Glory ).
Interrupts provide a chance for the opposing force to react to character actions and provide a means to suppress that enemy's reaction with covering fire, for example. The degree of success will be determined by a task roll and the amount by which the task number is surpassed.
To interrupt a character's turn should be have a difficulty of "routine" if the interrupted player is in the interrupter's forward arc and "difficult" if in the interrupter's side arcs. It is a confrontational task with AP's and tactics being the dm's.
If the task roll fails, then the amount that the task roll failed by is the number of AP's the interrupter loses although he can still act on his turn as per the MT interrupt procedure.
If the task roll succeeds, the amount by which it succeeds is subtracted from the interrupted's AP total and that becomes the number of AP's the interrupted may spend before the interrupter may act. The interrupter subtracts that number from his AP total to determine how many AP's has to spend during his interrupt. After the interrupt is completed, the interrupted character finishes spending his remaining AP's, assuming that he wasn't wounded so as to have a lower AP total ( damage takes effect immediately for purposes of AP and dm determination ).
Sgt Andy with 6Ap's and tactics-1 steps into a passageway to move down it. Mr. Enemy with 7AP's and tactics-0 attempts an interrupt ( routine, dm=+7-6(AP difference)+0-1(tactics difference)=0, and rolls 8.
This is 2 more than the target number, so Sgt Andy can perform (6-2) 4 AP's which include the initial AP spent moving into the passageway ( leaving 3 AP's ). Sgt Andy may react to Mr.Enemy's interupt with those 3 AP's by ducking back into cover or by sprinting or even returning fire. After those 3 AP's are spent by Sgt Andy, Mr.Enemy has 2 AP's he may spend ( initial 6-4=2 ). Mr.Enemy brings his SMG up ( 1AP ) and wants to spray the passageway.
Cpl Bobby with 5 AP's and tactics-0 attempts to interrupt Mr.Enemy's turn ( routine. dm=(5-7)+(0-0)=-2 and rolls a 5. He fails to interrupt and it costs him 3 AP's leaving him 2 AP's to spend when he takes his normal turn ( 5-2-6=-3, the task roll with dm's missed the target number by 3 ).
Mr.Enemy shoots and hits Sgt Andy, grazing him and the damage ends up lowering Sgt.Andy's AP to 5 ( damage takes effect immediately ). This leaves 1 AP as Sgt Andy has already spent 4. If Sgt Andy had taken enough damage to drop his AP count lower than 4, his turn would have ended then. Mr.Enemy's interrupt is over and Sgt Andy moves towards cover with his last 1AP.
All interrupts are over.
Cpl Bobby takes his normal turn and uses his 2 remaining AP's to shoot at Mr.Enemy wounding him badly. Too bad that Cpl Bobby was too slow......
Next turn begins...
That's how it works.
More play-testing is needed.
A way to determine when a character is knocked down by his wounds or other impacts needs to be made (damage will be determined from momentum for projectiles as well as with melee weapons, so that should play a role in knockdown/knock-back
Methods to work melee combat into this still need to be examined.
Maybe a character should have the option of providing dedicated covering fire whereupon he can do nothing else and can interrupt any target in his forward firing arc until his AP's run out AND drops the interrupt task level to "easy". If the interactions become too complex, it might be easier to use a master phasing count table instead.