EMPIRE(6) Games EMPIRE(6)
empire - the wargame of the century
empire [-w water] [-s smooth] [-d delay] [-S save-interval] [-f savefile]
Empire is a simulation of a full-scale war between two emperors, the computer and you.
Naturally, there is only room for one, so the object of the game is to destroy the other.
The computer plays by the same rules that you do.
This option controls the amount of water on the map. This is given as the percentage
of the map which should be water. The default is 70% water. water must be an integer
in the between 10 and 90 inclusive.
This controls the smoothness of the map. A low value will produce a highly chaotic map
with lots of small islands or lakes. A high value will produce a map with a few
scattered continents. Be forewarned that a high value will cause the program to take a
long time to start up. The default value is 5.
This option controls the length of time the computer will delay after printing
informational messages at the top of the screen. delay is specified in milliseconds.
The default value is 2000 which allows the user two seconds to read a message.
empire -w90 -s2
This produces a map with many islands.
empire -w50 -s0
This produces a really strange map. These values are not recommended for the faint at
This produces a map with lots of land and a few lakes. The computer will have a hard time
on this sort of map as it will try and produce lots of troop transports, which are fairly
There are two other option.
sets the save interval for the game (default is 10). Once per interval turns the game
state will be automatically saved after your move. It will be saved in any case when
you change modes or do various special things from command mode, such as `M' or `N'.
Set the save file name (normally empsave.dat).
Empire is a war game played between you and the computer. The world on which the game
takes place is a square rectangle containing cities, land, and water. Cities are used to
build armies, planes, and ships which can move across the world destroying enemy pieces,
exploring, and capturing more cities. The objective of the game is to destroy all the
enemy pieces, and capture all the cities.
The world is a rectangle 60 by 100 squares on a side. The world consists of sea (.), land
(+), uncontrolled cities (*), computer-controlled cities (X), and cities that you control
The world is displayed on the player's screen during movement. (On terminals with small
screens, only a portion of the world is shown at any one time.) Each piece is represented
by a unique character on the map. With a few exceptions, you can only have one piece on a
given location. On the map, you are shown only the 8 squares adjacent to your units. This
information is updated before and during each of your moves. The map displays the most
recent information known.
The game starts by assigning you one city and the computer one city. Cities can produce
new pieces. Every city that you own produces more pieces for you according to the cost of
the desired piece. The typical play of the game is to issue the Automove command until you
decide to do something special. During movement in each round, the player is prompted to
move each piece that does not otherwise have an assigned function.
Map coordinates are 4-digit numbers. The first two digits are the row, the second two
digits are the column.
The pieces are as follows:
│Piece │ You │ Enemy │ Moves │ Hits │ Str │ Cost │
│Army │ A │ a │ 1 │ 1 │ 1 │ 5(6) │
│Fighter │ F │ f │ 8 │ 1 │ 1 │ 10(12) │
│Patrol Boat │ P │ p │ 4 │ 1 │ 1 │ 15(18) │
│Destroyer │ D │ d │ 2 │ 3 │ 1 │ 20(24) │
│Submarine │ S │ s │ 2 │ 2 │ 3 │ 20(24) │
│Troop │ T │ t │ 2 │ 1 │ 1 │ 30(36) │
│Transport │ │ │ │ │ │ │
│Aircraft │ C │ c │ 2 │ 8 │ 1 │ 30(36) │
│Carrier │ │ │ │ │ │ │
│Battleship │ B │ b │ 2 │ 10 │ 2 │ 40(48) │
│Satellite │ Z │ z │ 10 │ -- │ -- │ 50(60) │
The second column shows the map representation for your units.
The third shows the representations of enemy units.
Moves is the number of squares that the unit can move in a single round.
Hits is the amount of damage a unit can take before it is destroyed.
Strength is the amount of damage a unit can inflict upon an enemy during each round of an
Cost is the number of rounds needed for a city to produce the piece.
The number in parenthesis is the cost for a city to produce the first unit.
Each piece has certain advantages associated with it that can make it useful. One of the
primary strategic aspects of this game is deciding which pieces will be produced and in
Armies can only move on land, and are the only piece that can move on land. Only armies
can capture cities. This means that you must produce armies in order to win the game.
Armies have a 50% chance of capturing a city when they attack. (Attacking one's own city
results in the army's destruction. Armies that move onto the sea will drown. Armies can
attack objects at sea, but even if they win, they will drown.) Armies can be carried by
troop transports. If an army is moved onto a troop transport, then whenever the transport
is moved, the army will be moved with the transport. You cannot attack any piece at sea
while on a transport.
Fighters move over both land and sea, and they move 8 squares per round. Their high speed
and great mobility make fighters ideal for exploring. However, fighters must periodically
land at user-owned cities for refueling. A fighter can travel 32 squares without
refueling. Fighters are also shot down if they attempt to fly over a city which is not
owned by the user.
Patrol boats are fast but lightly armored. Therefore they are useful for patrolling ocean
waters and exploring. In an attack against a stronger boat, however, patrol boats will
suffer heavy casualties.
Destroyers are fairly heavily armored and reasonably quick to produce. Thus they are
useful for destroying enemy transports which may be trying to spread the enemy across the
face of the world.
When a submarine scores a hit, 3 hits are exacted instead of 1. Thus submarines can
inflict heavy damage in a fight against heavily armored boats. Notice that healthy
submarines will typically defeat healthy destroyers two-thirds of the time. However, a
submarine will defeat a fighter about two-thirds of the time, while a destroyer will
defeat a fighter three-fourths of the time.
Troop transports are the only pieces that can carry armies. A maximum of six armies can be
carried by a transport. On any world containing a reasonable amount of water, transports
will be a critical resource in winning the game. Notice that the weakness of transports
implies they need protection from stronger ships.
Aircraft carriers are the only ships that can carry fighters. Carriers carry a maximum of
the number of hits left of fighters. Fighters are refueled when they land on a carrier.
Battleships are similar to destroyers except that they are much stronger.
Satellites are only useful for reconnaissance. They can not be attacked. They are launched
in a random diagonal orbit, and stay up for 50 turns. They can see one square farther than
All ships can move only on the sea. Ships can also dock in a user-owned city. Docked ships
have damage repaired at the rate of 1 hit per turn. Ships which have suffered a lot of
damage will move more slowly.
Because of their ability to be repaired, ships with lots of hits such as Carriers and
Battleships have an additional advantage. After suffering minor damage while destroying
enemy shipping, these ships can sail back to port and be quickly repaired before the enemy
has time to replenish her destroyed shipping.
The following table gives the probability that the piece listed on the side will defeat
the piece listed at the top in a battle. (The table assumes that both pieces are
│ │ AFPT │ D │ S │ C │ B │
│AFPT │ 50.0% │ 12.5% │ 25.0% │ 00.391% │ 00.0977% │
│D │ 87.5% │ 50.0% │ 25.0% │ 05.47% │ 00.537% │
│S │ 75.0% │ 75.0% │ 50.0% │ 31.3% │ 06.25% │
│C │ 99.6% │ 94.5% │ 68.7% │ 50.0% │ 04.61% │
│B │ 99.9% │ 99.5% │ 93.8% │ 95.4% │ 50.0% │
Notice, however, that when a ship has been damaged, the odds of being defeated can go up
quite a bit. For example, a healthy submarine has a 25% chance of defeating a battleship
that has had one hit of damage done to it, and a healthy submarine has a 50% chance of
defeating a carrier which has suffered two hits of damage.
There are a variety of movement functions. The movement functions of pieces can be
specified in user mode and edit mode. Cities can have movement functions set for each type
of piece. When a movement function for a type of pieces is set for a city, then every time
that type of piece appears in the city, the piece will acquire that movement function. Be
forewarned that moving loaded transports or loaded carriers into a city can have
undesirable side effects.
Normally, when a movement function has been specified, the piece will continue moving
according to that function until one of the following happen:
· An enemy piece or unowned city appears next to the piece. In this case the piece will
be completely awoken, unless its movement function has been set to a specific
destination. Armies on ships and pieces inside cities will not be awoken if the enemy
piece is gone by the time it is their turn to move.
· You explicitly awaken the piece.
· The piece can no longer move in accordance with its programmed function. In this case,
the piece will awaken temporarily. You will be asked to move the piece at which time
you may awaken it.
· The piece is a fighter which has just enough fuel (plus a small reserve) to get to the
nearest city. In this case, the piece will awaken completely, unless its movement
function has been set to a specific destination, or its movement function has been set
The rationale behind this complexity is that fighters must be awoken completely before
they are out of range of a city to prevent one from accidentally forgetting to waken the
fighter and then watching it fly off to its doom. However, it is presumed that when a path
is set for the fighter, the fighter is not in danger of running out of fuel.
Pieces do not completely awaken when their function has been set to a destination because
it is slightly time consuming to reset the destination, but very simple (one keystroke) to
wake the piece.
The movement functions are:
This function applies only to armies. When this function is set, the army will move
toward the nearest enemy city, unowned city, or enemy army. This is useful when
fighting off an invading enemy or taking over a new continent. When an army is set to
this mode, it will also explore nearby territory. This tends to make the "grope"
movement mode pretty useless.
When pieces are awake, you will be asked for the direction in which the piece should
move on each turn.
This function applies to carriers and transports. When this function is specified,
these ships sleep until they have been filled with fighters or armies respectively.
This function causes a piece to explore. The piece heads toward the nearest unseen
square of the map on each of its moves. Some attempt is made to explore in an optimal
This function applies to fighters and causes the fighter to head toward the nearest
transport or carrier.
This movement function causes a piece to move at random to an adjacent empty square.
This movement function puts a piece to sleep. The function of a city cannot be set to
This movement function only works on armies. The army sleeps until an unfull transport
passes by, at which point the army wakes up and boards the transport.
This movement function only works with ships. The ship will move to the nearest owned
city and remain there until it is repaired.
Pieces can be set to move in a specified direction.
Pieces can be set to move toward a specified square. In this movement mode, pieces
take a shortest path toward the destination. Pieces moving in accordance with this
function prefer diagonal moves that explore territory. Because of this, the movement
of the piece may be non-intuitive.
As examples of how to use these movement functions, typically when I have a new city on a
continent, I set the Army function of the city to attack. Whenever an army is produced, it
merrily goes off on its way exploring the continent and moving towards unowned cities or
enemy armies or cities.
I frequently set the ship functions for cities that are far from the front to
automatically move ships towards the front.
When I have armies on a continent, but there is nothing to explore or attack, I move the
army to the shore and use the transport function to have that army hop aboard the first
There are three command modes. The first of these is "command mode". In this mode, you
give commands that affect the game as a whole. In the second mode, "move mode", you give
commands to move your pieces. The third mode is "edit mode", and in this mode you can edit
the functions of your pieces and examine various portions of the map.
All commands are one character long. The full mnemonic names are listed below as a
memorization aid. The mnemonics are somewhat contrived because there are so few characters
in the English language. Too bad this program isn't written in Japanese, neh?
In all command modes, typing "H" will print out a screen of help information, and typing
<ctrl-L> will redraw the screen.
In command mode, the computer will prompt you for your orders. The following commands can
be given at this time:
Enter automove mode. This command begins a new round of movement. You will remain in
move mode after each of the computer's turns. (In move mode, the "O" command will
return you to command mode after the computer finishes its next turn.
Give the computer a random unowned city. This command is useful if you find that the
computer is getting too easy to beat.
The current round is displayed.
Examine the enemy's map. This command is only valid after the computer has resigned.
Print a copy of the map to the specified file.
This command gives the computer a free move.
Enter edit mode where you can examine and change the functions associated with your
pieces and cities.
Enter move mode for a single round.
Give the computer the number of free moves you specify.
Display a sector on the screen.
Quit the game.
Restore the game from empsave.dat.
Save the game in empsave.dat.
This command toggles a flag. When the flag is set, after each move, either yours or
the computer's, a picture of the world is written out to the file 'empmovie.dat'.
Watch out! This command produces lots of output.
This command allows you to watch a saved movie. The movie is displayed in a condensed
version so that it will fit on a single screen, so the output may be a little
confusing. This command is only legal if the computer resigns. If you lose the game,
you cannot replay a movie to learn the secrets of how the computer beat you. Nor can
you replay a movie to find out the current positions of the computer's pieces. When
replaying a movie, it is recommended that you use the -d option to set the delay to
around 2000 milliseconds or so. Otherwise the screen will be updated too quickly for
you to really grasp what is going on.
Display a condensed version of the map on the screen. The user map is divided into
small rectangles. Each rectangle is displayed as one square on the screen. If there is
a city in a rectangle, then it is displayed. Otherwise enemy pieces are displayed,
then user pieces, then land, then water, and then unexplored territory. When pieces
are displayed, ships are preferred to fighters and armies.
In move mode, the cursor will appear on the screen at the position of each piece that
needs to be moved. You can then give commands to move the piece. Directions to move are
specified by the following keys:
The arrow and keypad keys on your terminal, if any, should also work.
These keys move in the direction of the key from S. The characters are not echoed and only
1 character is accepted, so there is no need for a <Return>. Hit the <Space> bar if you
want the piece to stay put.
Other commands are:
Change the production of a city.
Set the function of a troop transport or aircraft carrier to fill.
Set the function of a piece to grope.
Set the direction for a piece to move.
Enter edit mode.
Wake up the piece. If the piece is a transport or carrier, pieces on board will not be
Set a fighter's function to land.
Cancel automove mode. At the end of the round, you will be placed in command mode.
Redraw the screen.
Set a piece's function to random.
Set a piece's function to sentry.
Set an army's function to transport.
Set a ship's function to upgrade.
Set the city movement function for the specified piece to the specified function. For
example, typing "VAY" would set the city movement function for armies to attack.
Whenever an army is produced in the city (or whenever a loaded transport enters the
city), the army's movement function would be set to attack.
Set an army's function to attack.
Display information about the piece. The function, hits left, range, and number of
items on board are displayed.
Attacking something is accomplished by moving onto the square of the unit you wish to
attack. Hits are traded off at 50% probability of a hit landing on one or the other units
until one unit is totally destroyed. There is only 1 possible winner.
You are "allowed" to do fatal things like attack your own cities or other pieces. If you
try to make a fatal move, the computer will warn you and give you a chance to change your
You cannot move onto the edge of the world.
In edit mode, you can move around the world and examine pieces or assign them new
functions. To move the cursor around, use the standard direction keys. Other commands are:
Change the production of the city under the cursor. The program will prompt for the
new production, and you should respond with the key corresponding to the letter of the
piece that you want produced.
Set a transport's or carrier's function to fill.
Set a piece's function to grope.
Set the function of a piece (or city) to the specified direction.
Wake all pieces at the current location. If the location is a city, the fighter path
will also be canceled.
Select the piece or city at the current location. This command is used with the "N"
Set the destination of the piece previously selected with the "M" command to the
Exit edit mode.
Display a new sector of the map. The map is divided into ten sectors of size 20 by 70.
Sector zero is in the upper-left corner of the map. Sector four is in the lower-left
corner of the map. Sector five is in the upper-right corner, and sector nine is in the
Set a piece to move randomly.
Put a piece to sleep.
Set an army's function to transport.
Set a ship's function to upgrade.
Set the city movement function for a piece.
Set an army's function to attack.
Display information about a piece or city. For a city, the production, time of
completion of the next piece, movement functions, and the number of fighters and ships
in the city are displayed.
Note that you cannot directly affect anything inside a city with the editor.
After you have played this game for a while, you will probably find that the computer is
immensely easy to beat. Here are some ideas you can try that may make the game more
· Give the computer one or more extra cities before starting the game.
· Try playing the game with a low smoothness value (try using the -s2 or even -s0
· When starting the game, the program will ask you what difficulty level you want. Here
"difficulty level" is a misnomer. To compute a difficulty level, the program looks at
each continent and counts the number of cities on the continents. A high "difficulty
level" gives the computer a large continent with many cities, while the user gets a
small continent with few cities. A low "difficulty level" has the opposite effect. It
may be the case that the computer will play better when the "difficulty level" is low.
The reason for this is that the computer is forced to move armies to multiple
continents early in the game.
According to A Brief History of Empire, the ancestral game was written by Walter Bright
sometime in the early 1970s while he was a student at Caltech. A copy leaked out of
Caltech and was ported to DEC's VAX/VMS from the TOPS-10/20 FORTRAN sources available
sometime around fall 1979. Craig Leres found the source code on a DECUS tape in 1983 and
added support for different terminal types.
Ed James got hold of the sources at Berkeley and converted portions of the code to C,
mostly to use curses for the screen handling. He published his modified sources on the net
in December 1986. Because this game ran on VMS machines for so long, it has been known as
In 1987 Chuck Simmons at Amdahl reverse-engineered the program and wrote a version
completely in C. In doing so, he modified the computer strategy, the commands, the piece
types, many of the piece attributes, and the algorithm for creating maps.
The various versions of this game were ancestral to later and better-known 4X
(expand/explore/exploit/exterminate) games, including Civilization (1990) and Master of
In 1994 Eric Raymond colorized the game.
holds a backup of the game. Whenever empire is run, it will reload any game in this
holds a history of the game so that the game can be replayed as a "movie".
No doubt numerous.
The savefile format changed incompatibly after version 1.13.
Satellites are not completely implemented. You should be able to move to a square that
contains a satellite, but the program won't let you. Enemy satellites should not cause
your pieces to awaken.
Original game by Walter Bright. Support for different terminal types added by Craig Leres.
Curses support added by Ed James. C/Unix version written by Chuck Simmons. Colorization by
Eric S. Raymond. Probability table corrected by Michael Self.
Copyright (C) 1987, 1988 Chuck Simmons
See the file COPYING, distributed with empire, for restriction and warranty information.
1. A Brief History of Empire
empire 01/05/2016 EMPIRE(6)