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 are some equipment which are useful for all combat ships. It goes without saying every ship should have Battle pods, because more space is good. For extra survivability you could choose either Reinforced hull or Heavy armor. Even though the description says Heavy armor stops armor piercing weapons, at least Graviton beams are capable of punching through it. 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.

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.

Main Weapons

 * For offense: beam weapons with the best modifications available, with the Heavy mount recommended.
 * For defense: Point defense beams with the best modifications to stop incoming missiles or to finish off weak targets.

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.

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).

Drone
'The Drone' is a small, very specialized design, which only comes available mid to late game. It carries no weapons, and 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.