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While you are starting a game you have to take some important decisions. This page describes the main ideas in the game, so that you will know the implications of the decisions you make during start-up.


Long before the time in which the game starts, two extremely powerful races, known as the Orions and the Antarans, fought a war that devastated most of the galaxy. The Orions were triumphant and, rather than exterminate the Antarans, imprisoned them in a "pocket dimension". The Orions then departed from the galaxy, but left behind a very powerful robotic warship, the Guardian, to guard their homeworld. Whoever beats the Guardian gets: some military technologies which players cannot research for themselves; the allegiance of the last remaining Orion, who commands a very powerful battleship; and the opportunity to colonize the Orions' homeworld, which is as good as a planet can ever be.

Some time after the start of a game, the Antarans, breaking out of their dimension the Orions have banished them into, begin sending small fleets against players' colonies, simply to destroy rather than to invade.

Victory conditions[edit]

There are three ways to win - exterminate all opponents; get elected as the supreme leader of the galaxy; or lead a successful assault against the Antaran homeworld (via a Dimensional Portal). To get elected as the supreme leader, you need two-thirds of the total votes (abstentions count as votes against both candidates), and each empire's votes are based on its population. So getting elected requires some combination of conquest and diplomacy (see below).

Despite the game's name, conquering the Orion star system does not automatically win the game, although the benefits acquired from doing so makes it easier.

Stars and planets[edit]

This system has 1 colony (yellow arrow), one empty planet which can be colonized, 2 gas giants and 1 asteroid belt (the gray dotted ring).

Most of the stars are "normal" and most of these have planets. Black holes have no planets and fleets that travel too close to them may get sucked in, unless they have a leader with the "navigator" skill.

"Normal" stars have at most five colonizable planets, and a few have none. If you have a colony in a system which contains gas giants or asteroid belts, you can eventually convert these to artificial planets and colonize them.

You can colonize all types of planets except gas giants or asteroid belts, but they vary in several ways, making some more desirable than others:

  • Population capacity, which on most planets can be improved by terraforming. "Toxic" planets cannot be terraformed.
  • Ease of growing food - this is important for the reasons described below. At the start of the game most planets are incapable of supporting agriculture, but terraforming can remedy this, except on "toxic" planets.
  • Mineral resources, which determine how quickly the player can build things there.
  • In a few cases, the presence of artifacts left by long-departed advanced races makes research more productive.
  • A few planets have natives, who can only grow food but do that more efficiently than any playable race.
  • Gravity outside a race's preferred range can reduce productivity in farming, industry and research.
  • A few planets have gold or gem deposits which increase the cash revenue from colonies there.
  • Very few planets contain "splinter colonies", which automatically join the empire which discovers them and acquire its racial advantages and disadvantages.

The most desirable systems are usually guarded by space monsters, much less powerful than Orion's Guardian but still a severe challenge in the early game, when fleets are small and low-tech.

How an empire's economy works[edit]

You can manage your empire's economy almost entirely from the Colony List.

Without food, a colony will starve to death (unless its population are "Lithovores"; see "Playable races" below). If your empire as a whole has a food surplus, you can save colonies from starvation by sending food in freighters, but using these costs money. Just one tiny hostile warship can prevent this by blockading a whole system, which makes turtling a risky strategy.

You can change a colony's output by moving colonists between farming, industry and research, except that natives can only farm. You can research and construct buildings which improve a colony's productivity in one or more of farming, industry and research. These game elements came almost directly from an earlier Simtex game, Master of Magic.

If the gravity of a planet falls outside of the gravity range your race is accustomed to, productivity is reduced, but you can research and construct a building that remedies this.

Pollution is a serious constraint on industrial production in the early game (unless its population are "Tolerant"; see "Playable races" below), but you can research technologies which reduce or eliminate it (all but one of these technologies require new buildings).

Maintaining buildings costs money and so does running an excessively large fleet. All colonists pay a standard tax to your treasury and in emergencies you can set a higher tax rate, but this reduces industrial production. You can also improve cashflow by researching and constructing certain buildings in larger colonies. You can use surplus money to accelerate production at selected colonies, but not to increase agricultural or research output.

Ships of different sizes require different numbers of "command points", which are provided by orbital bases, which are major construction projects for small colonies. You can research technologies which increase the command points provided by orbital bases. An empire can be ruined financially if its fleet requires more command points than its orbital bases provide, because "buying" extra command points is very expensive. This severely limits the size of empires' fleets; before you research technologies which increase the command points provided by orbital bases, you can have only one frigate (smallest type of ship) per starbase or one battleship (largest type of ship in the early game) per 4 starbases without having to "buy" command points.

The technology tree[edit]

The research menu at the start of a game. The highlighted tech area is being researched.

There are 8 technology areas:

Industrial buildings; planet-based defenses; larger types of orbital base and ships.
Armor; missiles; pollution control buildings; upgrades to the range of your ships.
Research buildings; buildings which increase all productivity by raising morale; targeting systems for warships.
Beam weapons; scanners; upgrades to command points provided by orbital bases.
Bombs; torpedoes (weapons which are similar to missiles); upgrades to the speed and firepower of your ships.
Relations with alien races; improving the performance of warships' crews; buildings to improve cashflow; upgrading your government (see below).
Buildings to improve farming productivity; biological weapons; technologies to increase population growth rates and reduce the damage done by biological weapons; terraforming.
Force fields
Shields; ship weapons which resemble machine-guns; ship components which improve maneuverability and make them harder to hit; cloaking.

Each technology area is divided into several levels, each of which contains 1 to 3 technologies. You can only research one technology at a time. To research a higher-level technology, you must first have researched the previous level. In theory one could research all levels of one subject area and neglect the rest, but this is usually suicidal.

"Creative" races get all the technologies at a particular level by completing one research project at that level; most races must choose only one technology from each level; "uncreative" races get no choice and the game software randomly selects a technology for them at each level. The way in which technologies are spread around the tech tree reduces the risk that an uncreative race will be left in a completely hopeless position, but looks rather odd.

Players can also acquire technologies by trading, spying, conquest, being the first to visit an artifacts planet or hiring a leader who can provide a technology.


For more details on diplomacy, see Master of Orion II: Battle at Antares/Diplomacy and intelligence.

Master of Orion II provides a wide range of diplomatic negotiations: gifts of money or technology or even all the colonies in a star system; opportunities to demand such concessions from other players; one-time technology trades; trade, non-aggression and alliance treaties. But the most effective way to gain favor with an AI player is to attack another AI player with whom the first is at war.

"Repulsive" races have only two diplomatic options: "Surrender" (which loses the game) and "Declare war".

The "Races" (diplomacy) screen also enables the player to allocate spies between defensive duties and spying or sabotage against other empires.

Spaceship design[edit]

The design of colony ships, freighters and troop transports is fixed, although they benefit from technology advances which increase the travel range, scanning range and speed of all your ships free of charge. These 3 ship types will be destroyed instantly if they travel without an escort and are attacked by anything, even the weakest combat ship.

Players can design warships, provided they choose the "tactical combat" option in game set-up. One can design a maximum of 5 classes at a time, but can have an indefinite number of classes in operation.

One can refit ships to take advantage of technology improvements which do not provide free upgrades.

Combat and invasion[edit]

Master of Orion II's space combat screen. In this example the battleships on the left are attacking the colony on the right, which is defended by a starbase. The space combat screen shows part of a larger, scrollable map.

Ships can travel to any star system within their range, unlike games such as Space Empires or Ascendancy where interstellar travel is possible only via "wormholes". Hence in Master of Orion II you cannot create easily-defended choke points.

Space combat occurs in two types of location: in orbit over a planet you are attacking or defending; and on the outskirts of a system, if one side is driving away the other's blockaders. It is impossible to intercept enemy ships in deep space. Limitations on the size of empires' fleets (command points, see above) mean that most battles involve only a handful of ships on each side. Ships do not stack, but move and fire individually.

At the start of a game you choose whether space combat should be "tactical" (controlled by the player) or "strategic" (controlled by the software); but choosing strategic combat prevents you from designing your own ships. In tactical combat the screen has an "Auto" button which makes the software take control of the player's ships and finish the battle.

You can only invade planets when all defending ships, orbital bases and planet-based defenses have been destroyed or forced to retreat. In order to invade, the attacking fleet must include some troop transports, which will be lost if the invasion fails, and at least one will be lost (deployed on the planet) if the invasion succeeds.

You cannot control ground combat: the result depends on numbers, ground combat technologies and racial ground combat bonus (some ship officers also give a bonus). But you see a display which shows the progress of the combat and the ground combat technologies and bonuses used by each side.

Recently-invaded colonies are disaffected and have poor productivity, but slowly improve, and there are ways to speed up the improvement. There is also a risk that recently-invaded colonies may rebel and rejoin the empire which founded them.

Instead of invading, you can destroy enemy colonies. This is cheaper in the short run but invading has longer-term advantages if successful: you may steal a technology; the newly acquired colony extends the range of your ships; the colony will contribute to your economy and research.

Telepathic races (see "Playable races") can mind-control enemy populations instead of invading with troop transports; but mind-control is thwarted if the defending colony belongs to a telepathic race or is governed by a telepathic leader. Telepathic races also assimilate conquered populations instantly, without a period of disaffection or risk of rebellion.


From time to time players get opportunities to hire leaders, for a hiring fee and annual salary. Colony leaders improve the farming and/or industrial and/or research and / or financial productivity of all colonies in the system to which they are assigned. Ship leaders improve the combat effectiveness of their ships and sometimes their travel speed. A few leaders of both types also improve the performance of ground troops under their command, or contribute directly to a player's finances. And a few are "famous", making other leaders more likely to offer their services, usually for a very small hiring fee and salary.

Random events[edit]

From time to time there are lucky breaks, disasters or emergencies which are not caused by the player's actions. These can be disabled in the game start-up menu.

Playable races[edit]

The Race design menu. Options that are highlighted have been selected.

Master of Orion II provides 13 pre-defined playable races: the Alkari, Bulrathi, Darloks, Elerians, Gnolams, Humans, Klackons, Meklars, Mrrshan, Psilons, Sakkra, Silicoids, and Trilarians (the Elerians, Gnolams, and Trilarians are new since MoO I). In addition to these, the game allows players to create custom races. As most players use custom races, it is more helpful to describe the range of racial characteristics from which you can choose rather than to describe the pre-defined races.

Each player starts with 10 "picks" (race design points). Choosing advantageous traits reduces the number of picks available, while choosing disadvantages increases them, but you cannot choose more than 10 picks' worth of disadvantages. So you get to choose at most 20 picks' worth of advantages.

Most of the options are easy to understand: major or minor advantages and minor disadvantages in farming, industry, research, population growth, money, space combat, espionage and ground combat.

Races from high-gravity homeworlds are fully productive on high-G and normal-G planets, and only mildly handicapped on low-G worlds; low-G races are severely handicapped on normal-G planets and practically helpless on high-G worlds.

"Creative" races research all the technologies at each level by completing one research project; all other races must choose one technological application to develop out of a given research project; "uncreative" races get no choice and the software randomly selects an application to be developed out of each research project undertaken. "Creative" is the third most expensive option, and typically provides greater advantages the longer a game lasts, because there are technologies to modify and enhance almost all abilities and aptitudes - so a race which has researched every productivity-enhancing technology researched can generally outperform all other races in their own specializations.

"Subterranean" races have a higher population limit on colonized planets, and have a small bonus in ground combat while defending.

"Tolerant" races have a higher population limit on colonized planets than most other races, and their industrial productivity is not reduced by pollution. This is one of the two most expensive options.

"Aquatic" races have more productive farming and higher populations on "wet" planets (Tundra, Ocean, Swamp, Terran) than other races. Note: although quite a lot of types of planet are "wet", at the start of a game the great majority of planets cannot support farming at all.

"Lithovores" feed on the natural minerals of a planet, and do not need to farm. This is one of the two most expensive options.

"Cybernetic" races need half as much food as non-cybernetic races, but each population unit also "eats" half a unit of industrial production. They can also repair ships during combat from the start, while other races must research Automated Repair Units and install them in their ships (reducing the space available e.g. for weapons) if they want their ships to repair themselves during combat.

"Transdimensional" races travel through space a little faster than other races at the same propulsion technology level. They can also travel through space (very slowly) without researching any ship drive technology, or when all interstellar travel is otherwise prevented by a hyperspace flux.

"Charismatic" races receive a large advantage in diplomacy, and more opportunities to hire leaders and at lower cost. "Repulsive" races have disadvantages in diplomacy and in choice and cost of leaders. Repulsive races cannot form alliances, sign treaties, or do any diplomatic contracts aside from declaring war, surrendering, and suing for peace.

Telepathic races have advantages in diplomacy and espionage, and can also conquer planets by mind control when they have overcome the defenses, instead of having to use troop transports to invade. Mind-controlled populations are instantly assimilated into your empire. Note that mind control does not work against another telepathic race, nor in a system where a telepathic leader is present.

Omniscient races can see all planets and ships (even those with cloaking devices).

"Fantastic traders" do better out of trade treaties than most, and get more tax revenue.

Lucky races get more favorable random events than most and far fewer disasters or emergencies, and tend to be overlooked by marauding Antarans.

Warlord races have an advantage in space combat and command points per orbital base.

You can also choose your empire's form of government, which has almost as much influence on how it performs as the choices described above, but the "best" governments cost a lot of picks. Dictatorships are the most common governments for the pre-defined races, and cost no picks. Democracy provides major advantages in research and money, but is the most vulnerable to spying and sabotage. Unification government provides advantages in farming, industrial production and security but none in research, and does not benefit from buildings that improve morale. Feudalism provides a large reduction in spaceship construction costs, but suffers from very slow research; the race design menu treats it as a significant disadvantage. Each government can be upgraded once by research, but the upgrades mostly increase the advantages of each without decreasing the disadvantages.

As a result of the wide range of choices, quite a lot has been written about race design for Master of Orion II.[1] [2]

User interface[edit]

The main screen: the pop-up window displays information about a specific star system, while the large window under it displays the galaxy as a whole.

This is mainly mouse-driven, but some screens also have hotkeys for important functions.

The main screen consists mainly of a zoomable (not scrollable) map of the galaxy. Stars have names which are color-coded to show which empires have colonies round them. Clicking on a star that you have already visited produces a pop-up window which shows the planets round that star. Clicking a fleet allows you to give orders and displays a pop-up which shows each ship in the fleet. Dotted lines show ship movements. The buttons along the bottom give access to various menus. The icons on the right provide information about the status of the empire and access to additional menus.

Colony List, with sort buttons along the bottom. The cursor (hand) on the right is about to open a colony's build menu.

Players can manage their economies almost entirely from the Colony List, which can be sorted by any of one of: Name, Population, Food production, Industrial production, Research production, the item currently being built, or Cash (BC) generated. The Colony List allows the player to access any colony's Build Menu, and to change a colony's output by moving colonists between Farmers, Workers and Scientists.

The Build Menu allows the player to queue up to 7 items (buildings, ships or spies) for construction at a colony, to refit ships in that colony's system and to design ships which may then be built at any colony.

At the end of each turn Master of Orion II shows a report in which items link to the appropriate display, usually to a colony's Build menu when a construction project has been completed.

The Information menu gives access to: a History Graph which shows how the player's empire compares with rival empires; the racial characteristics of all empires with which the player is in contact; the technologies the player has researched; and descriptions of all technologies, including the exotic ones which the player cannot research but may gain by beating Orion's Guardian.

Beginning a game[edit]

When the program loads[edit]

You can skip the splash screens and go straight to the start menu by hitting the ESC key. The start menu's options all have hot keys:

C = Continue
MOO II automatically saves every 4 turns, and when you close the game down. "Continue" loads the automatically saved game.
L = Load game
Loads a saved game.
N = New game
Starts a new single-player game by displaying the New Game Menu.
M = Multiplayer
This displays the Multiplayer Setup Menu
H = Hall of Fame
Displays the 10 highest scores.
Q = Quit
Closes the game down.

Starting a new single-player game[edit]

New Game Menu[edit]

The New Game Menu.

All of the New Game Menu's options work by clicking until it cycles round to what you want - there are no drop-down lists or radio button groups. It asks you to specify:

  • Difficulty level - "Tutorial" is easiest, "Impossible" is hardest. On the harder levels the other empires are stronger and more likely to be hostile.
  • Galaxy size. Small galaxies lead to very early contact and probably combat and / or attempts to steal technologies from you.
  • Galaxy age. The manual say "old" galaxies have more planets that allow farming but fewer rich or ultra-rich planets; while "young" galaxies are the opposite. But in practice there seems to be little difference.
  • Number of players. The greater the number, the sooner you make contact.
  • Tech level. MOO II has 3 starting tech levels:
    • "Pre-warp", where you have no ships, and you have to research everything.
    • Average, where you start with a small fleet and a few technologies. Note that if your race is not Creative the game gives you a random selection of technologies and they might not be what you would want. On the other hand a Creative race gets all the technologies in the levels that have been "researched".
    • Advanced, where you start with a slightly larger fleet and a few more technologies. Being Creative is an even greater advantage in Advanced starts.
  • Tactical or strategic combat. Always choose tactical combat, otherwise you can't design your own ships and can only use those generated by the game software, which are usually not very good. If you don't want hands-on control of combat, just click the "Auto" button at the beginning of each battle.
  • Whether random events are allowed.
  • Where the Antarans are allowed to attack colonies. If they are not, you can't conquer them, which is the highest-scoring type of victory.

Race Selection[edit]

The next screen is the Race Selection Menu, which invites you select one of the pre-defined races or design your own. If you select a pre-defined race, no enemy empire will be of the same race.

If you select "Custom Race", you will see the "Select Race Picture" Screen. You have to choose one of the pre-defined race pictures, and you will not meet another empire of that race in the game.

Then you get one of the most important screens in the game, the Race Design Menu. See Race design for more details.

Naming your ruler and home system[edit]

These 2 screens are easy - you can just click "accept" unless you want the Hall of Fame screen to contain a unique ruler name for each entry. The Ruler Name and Home System Name screens have a small bug - the maximum length of the name varies from one game to another and sometimes is as short as 6 characters.

Then you see the game's Main Screen, which is described in Game controls.


  1. Master of Orion II Strategy Guide at
  2. Master of Orion II Custom Race Archive at