Master of Orion II: Battle at Antares/Warship design

Warship designs vary by the phase of the game, and depend on the production capacity and technology available. One of the most important decisions is to decide which size class(es) to use. Early on, Titans and Doom stars are not available until their relevant Construction techs are researched, which happens usually mid to late game. It is entirely possible to build a powerful fleet without using Titans or Doom stars at all.

Generally, as the ship size increases, the price per space unit and the price per structure point increases. Also the size of the special systems is scaled upwards with the ship class. From this point of view, it would make sense to build a fleet of many small ships. The problem for non-Warlord races is the limited number of command points, of which many small ships will quickly consume. One solution is to build a fleet of solely Battleships, since those are available right from the beginning. One factor deciding size class is also the attack strength of the enemy: if you know the larger ships are capable of soaking up any damage until the enemy is destroyed, and the smaller ones are not, build the larger ships. On the other hand, if you are fighting a powerful space monster which would surely destroy some ships, build a fleet of many small craft, so that the monster can't destroy all of them in one turn.

Design advice for all warships
There is some equipment which is useful for all combat ships. It goes without saying every ship should have Battle Pods, because more space is good, unless of course it makes the ship too expensive to build. For extra survivability you could choose either Reinforced Hull or Heavy Armor. Heavy Armor does negate armor piercing effects, but it is worth noting that Graviton Beams are capable of doing damage directly to structure and Ion Pulse Cannons to systems. Also, it is bypassed by the Achilles Targeting Unit. The fact that having the structure points reach zero always destroys the ship, and any armor left at that point doesn't help at all, would make it more sensible to choose Reinforced Hull when facing those weapons.

Beam Ship
Beam ships are specialized for attacking enemy ships, star bases and planet defenses. The heavy mount modifications make them effective from the first turn of combat because of the long range. Battle Scanner and a good targeting computer are necessary to ensure high ship initiative and beam hit rates. Closer to the end-game, beam ships equipped with all the damage-enhancing systems can quickly overrun any opponent, even if his fleet is numerically much superior.

Early in the game, when you still have ineffective targeting computers and the enemy doesn't yet have decent shield technology or drives, you can still make an effective beam ship using the Point Defense modification. Pd-weapons have an inherent +25% accuracy bonus, and most can be further modified with Continuous fire thereby raising their accuracy another 25%. They do 50% less damage, but take up 50% less space, so you simply need to add twice as many to your hull design to get the same damage output as you otherwise would have using "normal" beams. Both Mass Drivers (inherent) and Lasers (modified) add the further advantage of zero range dissipation and armor piercing, meaning they don't actually have to fire point-blank to do full damage while bypassing a substantial part of the enemy's defense. This type of ship usually needs Augmented Engines and a decent drive to be effective, both to increase it's own defensive beam rating and for closing range to the target. The down-sides are that Pd-weapons can't harm planetary defenses, and Class-III shields generally make this type of design obsolete. But for early-game rushing it can be a viable strategy. It also combines well with Troop Ships and Planetary Assault ships (see below).

Main Weapons

 * For offense: beam weapons with the best modifications available, with the Heavy mount recommended, or Pd-weapons only (early game).
 * For defense: Point defense beams with the best modifications to stop incoming missiles or to finish off weak targets. Note that the Pd modification isn't strictly necessary in shooting down missiles, in fact, in the later game it usually sensible to drop the Pd modification altogether, because it lowers the damage too much against high tech shields, and go for Auto-Fire Phasors/Disprupters only.

Special Systems

 * Battle Scanner: To have any reasonable chance of beams hitting the target, you'll need this system. It also raises the ship initiative (if enabled), which most of the time allows you to fire first, and destroy the enemy before they even get one shot off.
 * Structural Analyzer, Achilles Targeting Unit, High Energy Focus, Hyper-X Capacitors: These all increase the beam damage potential. Install all of them in the ship, if possible.
 * Some optional, good defensive systems: Inertial Stabilizer/Nullifier, Hard Shields, Multi-Phased Shields, Lightning Field, Damper Field, Automated Repair Unit, Cloaking devices etc. It depends on the situation which of these are the most useful, so use your judgment.

Missile Ship
Efficient Missile ships can be built from the earliest stages of the game. Missiles usually provide excellent damage and accuracy early on. Missile battleships with even the basic missiles can be used to take out monsters and destroy enemy Missile Bases/Star Bases in repeated hit-and-run attacks. The 2xAmmo modification helps launch the payload faster: 5 launchers with 2 rounds each will get your missiles out a lot faster (and thus damage at a higher rate) than 2 launchers with 5 rounds each. The armor and structure upgrades ensure the ship's survival.

Main Weapons

 * Missiles with the best modifications, 2xAmmo setting recommended. The order in which you place the missiles is important. The missiles placed in the top rows are targeted by Point defense first and also strike the enemy first. It makes sense to place the weaker missiles first for the enemy Pd to shoot at, and then have the fully modified (Mirv, EMG) missiles last. Also, when designing your missile ships, split your missiles into multiple weapon slots. This allows you to split targets for each group of missile independently. Consider what happens when a 2xAmmo ship meets with 3 ships that are much smaller than it - splitting up your weapons into multiple groups lets you target more efficiently.

Special Systems

 * Fast Missile Racks: These can be used in hit-and-run tactics to overwhelm the enemy with masses of missiles.
 * Useful techs to have: Dauntless Guidance System, Emissions Guidance System, any Sensor/Scanner techs to reduce enemy missile evasion.

Troop Ship
Troop Ships serve specifically to take out enemy Star Bases, or to occasionally capture enemy ships (especially Antaran). Their main element is the Troop Pods, doubling marines on board. A Troop Ship with a decent drive and Augmented Engines can reach the enemy star base in two combat turns and capture it. This can be used as a hit-and-run tactic, weakening the enemy fleet by destroying all of its star bases, or as a component of the overall attack tactic. Later on Battlestations and Star Fortresses have so much armor that capturing instead of destroying them might be much easier. Marine-killing weapons (Neutron Blaster/Death Ray) are a bonus.

Main Weapons

 * Neutron Blaster/Death Ray, if the enemy has much higher ground combat rating, or any beams to clear out shields before boarding.
 * 4x Tractor Beam, if capturing ships.

Special Systems

 * Troop Pods, Transporters.
 * Augmented Engines (early) or Sub-Space Teleporter (very late).

Auxiliary Ship
Auxiliary Ships are made to draw enemy fire or otherwise be extremely hard to kill, rather than to inflict damage. Thus they generally have no weapons and are employed for two main purposes:

Decoy
Single Player: This type of ship is meant to play on the AI's tendency to target what it perceives as the smallest or weakest ships first. Filling it with defensive systems forces the enemy to waste precious ammo/shots while your main battle line closes in for the kill. You can sometimes successfully draw swarms of enemy missiles and torpedoes away from your expensive Battleships this way.

Single- and Multi-player: This type is meant to allow your main attack ships to fire and flee. Thus it will be the last friendly ship to warp out of the battle, only retreating once all missiles and torpedoes have hit their targets. Since it will become the sole target of enemy forces for a turn or two, it must be extremely fast/hard to kill.

Electronic Warfare Drone
The 'EWD' is a small very specialized design, which only comes available mid to late game. The only essential systems are Warp Dissipator and Wide Area Jammer, because of their fleet-wide effects. It should be equipped with a Phasing Cloak (if possible) or any other defensive systems to get quickly out of the harm's way in combat.

Planetary Assault (PA) Ship
This ship class represents specialized designs meant to destroy stubborn stationary planetary defenses. Sometimes for one reason or another your otherwise quite effective ship designs just don't seem to get the job done when they attack an enemy planet, and refitting the entire fleet is unpractical (and unnecessary). Thus a PA Ship supplements your normal attack fleet and is used specifically against the particular alien defenses it was designed to thwart.

Weapons
PA Ships are the only class of ship where it makes sense to consider using bombs. However beams, missiles, torpedoes and bombers/heavy-fighters are all effective alternatives, with the following limitations: Planetary defenses (as well as the defending Starbase) generally have terrible beam defense ratings. Thus you can usually forego a Battle Scanner on a PA Ship and use the space to pack in more weapons.
 * The weapon must be effective against planets (ie. excludes most Special Weapons or Pd-weapons)
 * Be strong enough to overcome any planetary shielding.
 * Be of sufficient quantity to destroy whatever planetary installations are likely to be present.

Defensive Systems
Since the PA Ship will often become the (sole) target of the planetary defense it is trying to destroy, it will need to be equipped with sufficient Armor/Structure to last enough turns to get the job done. This usually entails:
 * Shields or Automated Repair Units and Inertial Stabilizer or Augmented Engines vs Ground Battery
 * ECM-Jammer and Pd-weaponry or Lightning Field vs Missile Base
 * Pd-weaponry or Lightning Field vs Fighter Garrison