Current system
In the current system, duration of a turn is quite long, and sides are frozen for a long period (well, except reaction fire). This causes the defending side gets an advantage: it may surprise the attacker (the side that advances) when it depleted its movement and when it is frozen. An example: the attacking soldier ends his turn 15 "distance" from a corner (or from any area the enemy may be hidden). An allien with a kerrblade is hidden there. The allien approaches during his turn. The soldier has no points for RF or his weapon is not effective enough to kill the allien, and so he waits hopeless for his death.
In real situation he would simply escape, or he would cry so that other comrade-in-arms (who may have his back turned on him) reacts and fire.
I would like a combat system that allows stronger and more natural defense against a surprise attack.
Shorter duration of a turn
This may be done if turns are shorter (you get a control more frequently): imagine about 5 TU per turn in place of 30 (I know I should differentiate between "seconds" (time is common for all soldiers) and "time units" (they differ depending on a soldiers), but for simplicity I suppose all soldiers have equal TU per turn).
It is true 5 TU is not enough to fire within a turn for most soldiers/weapons. But actions could pour from one turn into another, so a shot could be performed in more turns.
An example: a soldier has 5 TU per turn, 12 TU is needed for a shot, and the soldier has only 3 TU left and wants to fire. So you order a shot against a target in turn 1, and it is accomplished in turn 3 (3+5+4 TU are used in turns 1, 2, 3). (The target may move out of sight/range, and in this case the shot is stopped.)
Continous Time
The game could also use continuous time, or turns long 1 TU/second only.
Of course a player doesn't want to regain control each TU/second again and again. But he could "plan" his soldiers: in the current system you order only one action for a soldier, but you could order a chain of actions (for example go here, look right, continue here, look left, crouch ...). After you order chains for all soldiers, you click "go" button and time will start to flow. Time will stop once you get a new piece of information (for example new allien is spotted), and you can change your orders.