A suggestion I would like to make aims to significantly reduce the player's idle time during large encounters with many combatants.
The issue
One of the major downsides of turn based combat in RPGs is that the time a player has to wait in order to make his next turn linearly increases with the number of combatants taking part in the encounter. While games that feature real time with pause handle all combatant's turn simultaneously, turn based is at the disadvantage of having to wait several seconds for every single combatant to make his turn one after the other. In the worst case, this can lead to downtimes where the player has nothing to do other than lean back for minutes, waiting when your next turn is.
Suggestion
To alleviate this issue and make turn based combat more fluid and engaging I would suggest a system where enemy turns are grouped up based on their turn order and play out simultaneously. So instead of letting multiple individual turns play out, there is one single enemy group turn.
For example:
Character A and Character B of your party have both made their turn, now 5 goblins get to make their turn before your characters C and D get to make their turn and finish the round. So instead of having to wait for one goblin after another to make their turn, all 5 simultaneously start moving into position and perform their actions. Instead of having to wait for 5 individual turns to play out, you only have to wait for 1 turn where 5 combatants make their move.
Potential problem of this system
The advantage of reducing idle time for the player might come at the cost of losing some overview of what happens during one round of combat. This kind of issue of course is typical for real time with pause combat systems but is normally alleviated by having a detailed combat log where every action can be reviewed in case the player couldn't keep track of everything what happened during a turn.
Potential fix to keep better overview
Instead of just letting all enemies between you characters turns run wild and perform all their actions whenever they are ready to do so, the enemy group turn could be segmented into multiple phases.
Phase 1 would be an initial movement phase where enemies, if they need to change their position, do so simultaneously or keep their current position if they don't need to move. After every combatant has reached their position, phase 2 starts.
Phase 2 contains all enemies taking their planned action but this time the actions are not performed simultaneously. To keep a better overview all enemy actions play out one after another in the order of their individual position in the initiative queue. The camera focuses on each action and jumps from combatant to combatant. After all enemies have done so, phase 3 starts.
Phase 3 is another movement phase, where enemies can spend their movement points in case they haven't done so before or still have movement left which they want to spend. This happens once again simultaneously.
This can be followed up by an optional phase 4 where enemies perform a bonus action.
Closing thoughts
As there are many different players out there with many different preferences I would suggest to make this system optional, tucked away in the options menu for players to toggle on or off, whether they would like to use this more speedy version of turn based combat or keep the slower but easier to overview system which is currently in the game.
