Introduction

Tactical combat is fought at the star system scale, with turn lengths of several hours, in essence it is an operation level system. I have tried to remain true to the designers notes in Star Cruiser, even though I have to change things to do so.

1 Turn = 6 hours
1 Hex = 0.08 AU's
1 Unit = Individual Ship, Fighter or Missile
1 TG = A number of ships, fighters or missiles grouped together (for fighters such a group is refered to as a squadron, for missiles a salvo)

At this scale, the distance from Earth to the FTL point is 20 hexes.

Gun batteries are 4 similar weapons grouped together, but missiles are individual.

There are no launch restrictions on missiles, a Kennedy can have all 20 in one salvo, but none carry their own sensors.

Turn Order

Turns are resolved simultaneously, with 3 distinct phases:

Sensors Operations
Movement
Attacks and Secondary Movement
In the sensor ops phase, each side may attempt to make locks on the other, then movement (including missile and fighter operations) is resolved, finally, if any units (including missiles) end up in the same hex as enemy units, combat may occur.
Due to the PBEM nature of the game, secondary movements are allowed, as explained below.

Sensor Operations

Spot Range = (Sensor Rating * Enemy Signature) + Crew Quality - Targets CQ

Movement

There are no facings, you simply move a number of hexes equal to your Warp Efficiency*2, rounded to the nearest number.

Secondary Movement

A ship doesn't have to use all of it's movement in planned movement, it may leave 1 MP as a secondary movement, with a specific instruction. The most general uses for this are orders given to missiles and fighters to move and attack any enemy within 1 hex, or to retreat from close combat if contacted (and hope the enemy didn't leave a secondary movement to follow up).

Attacks

All combat is essentially beam combat, even missiles. There are 2 weapons systems in use, standard beam weapons, and det weapons. All combat is conducted in the same hex, and begins with an intercept attempt.

If both sides want to intercept (engage each other), then it is automatic. If neither does then it automatically doesn't. If one does and the other doesn't, then an Intercept Roll is made. The Base number is 5 + Interceptors Movement + Interceptors CQ - Evaders Movement - Evaders CQ. Roll d10, if equal of less then an intercept occurs.

Once a ship is intercepted, it is engaged in combat, and may no longer move unless it breaks off combat. Note that missile intercepts automatically break off immediately (as the missile either detonates or is shot down), and so no problems with movement occur.

Note that missiles also need to intercept to attack a target, thus agile (fast) ships may evade incoming missiles.

Once an intercept has occured, each side may fire every weapon they have. Combat is resolved as a sequence of broadsides until one side is either destroyed or breaks off, the tactical combat is so short compared too a 12 hour operational turn.

Standard beam weapons may each make 1 shot per combat turn. To determine how many hits, roll d10, add your Crew Quality and The Batteries Accuracy, and deduct target profile, if 7 or greater the shot hit.

Det-weapons are much the same, however, if the platform they are firing from is destroyed by enemy fire, the attack does not succeed. Each det weapon may be fired at by the targets batteries, and if hit is destroyed and does not make an attack.

Armour Penetration

Each hit must first roll to penetrate armour. The roll is d10, +1 for each weapon class above light. If greater than the ships armour value then the hit penetrated.

Damage

There are no HP's. Instead, each attack that penetrates armour may cause a hit. To simulate damage control, critical hits are grouped into minor, major and critical results. Roll d10 on the table (TBC), and deduct the DC modifier.
 
 

Note that missiles do not get replaced once used. The only replacements are those pulled of other ships, however, submunitions do get replaced.