empire - the wargame of the century
[-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
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 heart.
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 useless.
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
Set the save file name (normally
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
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 (O).
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
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:
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 attack.
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 what quantities.
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.
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.
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.
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.
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
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.
are similar to destroyers except that they are much stronger.
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 other objects.
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
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 undamaged.)
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
•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 to
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 fashion.
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 'sleep'.
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
Pieces can be set to move in a specified
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
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 passing transport.
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
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
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
This command gives the computer a free
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
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
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 awoken.
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
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
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 mind.
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
Set a transport's or carrier's function to
Set a piece's function to grope.
Set the function of a piece (or city) to the
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" command.
Set the destination of the piece previously
selected with the "M" command to the current square.
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 lower-right
Set a piece to move randomly.
Put a piece to sleep.
Set an army's function to
Set a ship's function to upgrade.
Set the city movement function for a
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
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 interesting.
•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 option).
•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
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 VMS Empire.
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
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 Orion (1993).
In 1994 Eric Raymond colorized the game.
holds a backup of the game. Whenever empire is
run, it will reload any game in this file.
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
Copyright (C) 1987, 1988 Chuck Simmons
See the file COPYING, distributed with empire, for restriction and warranty
- A Brief History of Empire