May be hard to implement, but easy to understand suggestion without wierd "rounds" or global turns or something.
For example you need 5.00 seconds to restore AP from 0% to 100%, but you can do that by different ways!
Sequence means reaction of a character, how he's fast in starting actions... bla bla bla, who cares what's sequence anyway, so it'll work like that:
You're blind moron with 1 PE and minimal possible sequence: 2, name is Character A.
He's 10 PE attentive kamikaze, who, for some crazy reason, took all possible sequence perks. 31 sequence, Character B.
Both, Character A and B, will have full ammount of AP from 0 to thier max AP in 5 seconds. But than more sequence you have than faster it replenish at the start and slower in the end, it'll look like this:
This way you can see that low sequence character will regen AP slower than high sequence at the start, but later, when he'll have =>50% he'll regen AP faster to compinsate it.
It'll make Earlier Sequence perk useful, the same about Kamikaze trait.
Fast Shots trait users will have an advantage with higher sequence because of low AP per shot usage, making this class more useful than now.
If say in words:
1)
Character A will have only 2 sequence, for example he has 10 AP.
He shots you twice in the head with a pistol, now he has 0 AP.
In the same time Character B, who has 31 sequence have the same ammount of AP and did the same.
In 1 second A will have almost... 1 AP, so still 0 APs, while B will have 3 AP already! (don't worry, it's a big sacrifice to take x3 earlier sequence perks so 31 sequence isn't reasonable...)
In 2 seconds A will have 2 APs, B will have 5 APs.
In 3 seconds A will have 3 APs, B will have 8 APs.
In 4 seconds A will have 6 APs, B will have 9 APs.
In 5 seconds A and B will have 10 APs.
2)
Character A is smart, he knows that if he'll lose all APs he'll restore it slowly, so he shots B's head only once!
Character B is smart too, so he shots his head twice!
In this case high sequence allows you to have less unspent APs to use your character in combat properly, while low AP forces you to leave some APs.
In this way:
A shot only once, he has 5 APs. it's 50% of his APs, so it's like starts from 2.5th second:
In 1 second A will have ~6 APs, B will have 3 APs.
In 2 seconds A will have ~9 APs, B will have 5 APs.
In between of 2 and 3 seconds A will have 10 APs.In 3 seconds A will still have 10 APs, B will have 8 APs.
In 4 seconds A will still have 10 APs, B will have 9 APs.
In 5 seconds A and B will have 10 APs.
Well.. it's some kind of suggestion.