If I have a fleet with 6 unused movement points on the enemy's turn, and they attack it with only 2 movement points, I should damn-well be allowed to say "Screw that noise" and pull them back!.
Why? If you didn't want the battle and you had enough movement points to end your turn beyond the enemy's reach, then you should have ended your turn somewhere beyond the enemy's reach.
Moreover, this game already greatly favors the aggressor; it does not need to compound that advantage by making it so that if the aggressor screws up by leaving ships within the striking range of potential threats (known or not) that the aggressor gets to get off scot-free at little cost to the aggressor's mobility. With even the speeds of the ships that the computer uses, it's already reasonably likely that interception attempts will only be possible for a turn before a strike fleet or invasion force reaches its target, even if the aggressor doesn't use all their actions every turn. Making many of these interception attempts quite likely to fail even without the involvement of actual battle fleets screws the defending side over even more than is already the case.
As far as strategic retreats go, they should absolutely be implemented ... as it's part of just about EVERY TURN-BASED STRATEGY GAME EVER!
My experience must be completely different from yours, because in my experience it would appear that the ability to execute a strategic withdrawal on the opponent's turn is not a common feature of turn-based strategy games. The only TBS games I can think of off the top of my head that allow me to execute a withdrawal at the strategic level on the enemy's turn without first fighting an engagement are all in the Total War series, and to be perfectly honest I do not consider that to be a positive feature of that series. I would also point out that the ability to make a strategic withdrawal is already in the game - you do, after all, have the ability to move your units as you choose on your turn, and if you choose to do so you can withdraw your forces rather than leaving them in more exposed positions.
I would furthermore point out that if the decision to withdraw is taken when the opposing forces meet, the withdrawal is much closer to being a tactical withdrawal than a strategic withdrawal, especially since said withdrawal would probably only involve the unit attacked and not directly cause the withdrawal of any of the other units of the same faction in the same area.
Why do you have to chase down fleets? The game is about taking planets so you make a strategic retreat with consequence.It is pretty stupid that my one scout is attacking a armada.Most have the option.This pissed me off in FE too.
To be perfectly honest, I am not terribly concerned about chasing down fleets when I'm the aggressor and close to winning or conquering a region, though that is still something worth caring about because it's far less risky for my fleets to hunt down individual ships or small fleets before they can group up than it is for me to destroy those same ships in a smaller number of larger fleet battles. It's more when I'm trying to defend that I care about having to chase down fleets; the aggressor already has a significant advantage in this game due to the very high movement speeds attainable and does not need to compound that with immunity to losses due to poor ship placement at the end of a turn. Stopping a high actions/turn fleet before it reaches its target is bad enough when it cannot save five or ten of its actions to tell your intercepting forces to go bugger themselves five or ten times before your intercepting forces can force a fight.
There is also the issue that the computer (or the player, if so inclined) could stack up a large number of individual units (whether ships or fleets just large enough not to be able to combine with one another) between me and a target, which I will then have to push through, wasting a number of actions equal to the number of fleets I have to push through or to the number of extra tiles I have to move to go around them. If these ships aren't destroyed when I push through them, the computer can do the same thing again and again and again, on the next turn and the one after that and the one after that, or on some future turns, or even on the same turn (depending on implementation; after all, under current mechanics it isn't clearly a good idea for retreating ships to leave the tile that they had occupied, as there could be other ships belonging to the same faction in that tile, which means that the attacking fleet cannot necessarily occupy the tile which the retreating unit had occupied, and if the retreating ships do get to move back a tile but the attacking fleet does not move into the attacked tile the attacking fleet now has to spend two actions to reengage; scattering the units on the tile occupied by the retreating unit is also problematic since one of the ways to protect a valuable but weak unit is to stack powerful units on top of it so that those units must be engaged to attack the weak unit, and it introduces conceptual issues if a fleet that retreats causes everyone else to run away but no one cares when a fleet in the same location is destroyed).
Also, just because one of the win conditions for the game is to conquer my enemies or otherwise acquire their worlds does not mean that my war objective has to be conquest. I play games to have fun; if the Drengin Empire declares war on me but I don't want to end the game yet, chances are that I'm not really going to go all out trying to conquer the Drengin Empire and I may well be satisfied with just wrecking their military.