Provided by: empire_1.14-1build1_amd64 
NAME
empire - the wargame of the century
SYNOPSIS
empire [-w water] [-s smooth] [-d delay] [-S save-interval] [-f savefile]
DESCRIPTION
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.
-wwater
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.
-ssmooth
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.
-ddelay
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.
EXAMPLES
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.
empire -w10
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.
-Sinterval
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'.
-fsavefile
Set the save file name (normally empsave.dat).
INTRODUCTION
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 (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 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.
PIECES
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 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.
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 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 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 undamaged.)
┌─────┬───────┬───────┬───────┬─────────┬──────────┐
│ │ 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.
MOVEMENT FUNCTIONS
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 to land.
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:
Attack
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.
Awake
When pieces are awake, you will be asked for the direction in which the piece should move on each
turn.
Fill
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.
Grope
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.
Land
This function applies to fighters and causes the fighter to head toward the nearest transport or
carrier.
Random
This movement function causes a piece to move at random to an adjacent empty square.
Sentry
This movement function puts a piece to sleep. The function of a city cannot be set to 'sleep'.
Transport
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.
Upgrade
This movement function only works with ships. The ship will move to the nearest owned city and remain
there until it is repaired.
<dir>
Pieces can be set to move in a specified direction.
<dest>
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 passing transport.
COMMANDS
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.
COMMAND MODE
In command mode, the computer will prompt you for your orders. The following commands can be given at
this time:
Automove
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.
City
Give the computer a random unowned city. This command is useful if you find that the computer is
getting too easy to beat.
Date
The current round is displayed.
Examine
Examine the enemy's map. This command is only valid after the computer has resigned.
File
Print a copy of the map to the specified file.
Give
This command gives the computer a free move.
J
Enter edit mode where you can examine and change the functions associated with your pieces and
cities.
Move
Enter move mode for a single round.
N
Give the computer the number of free moves you specify.
Print
Display a sector on the screen.
Quit
Quit the game.
Restore
Restore the game from empsave.dat.
Save
Save the game in empsave.dat.
Trace
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.
Watch
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.
Zoom
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.
MOVE MODE
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:
QWE
A D
ZXC
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:
Build
Change the production of a city.
Fill
Set the function of a troop transport or aircraft carrier to fill.
Grope
Set the function of a piece to grope.
Idir
Set the direction for a piece to move.
J
Enter edit mode.
Kill
Wake up the piece. If the piece is a transport or carrier, pieces on board will not be awoken.
Land
Set a fighter's function to land.
Out
Cancel automove mode. At the end of the round, you will be placed in command mode.
Print
Redraw the screen.
Random
Set a piece's function to random.
Sentry
Set a piece's function to sentry.
Transport
Set an army's function to transport.
Upgrade
Set a ship's function to upgrade.
Vpiece func
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.
Y
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 mind.
You cannot move onto the edge of the world.
EDIT MODE
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:
Build
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.
Fill
Set a transport's or carrier's function to fill.
Grope
Set a piece's function to grope.
Idir
Set the function of a piece (or city) to the specified direction.
Kill
Wake all pieces at the current location. If the location is a city, the fighter path will also be
canceled.
Mark
Select the piece or city at the current location. This command is used with the "N" command.
N
Set the destination of the piece previously selected with the "M" command to the current square.
Out
Exit edit mode.
Printsector
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 corner.
Random
Set a piece to move randomly.
Sentry
Put a piece to sleep.
Transport
Set an army's function to transport.
Upgrade
Set a ship's function to upgrade.
Vpiece func
Set the city movement function for a piece.
Y
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.
HINTS
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.
HISTORY
According to A Brief History of Empire[1], 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 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 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 Orion (1993).
In 1994 Eric Raymond colorized the game.
FILES
empsave.dat
holds a backup of the game. Whenever empire is run, it will reload any game in this file.
empmovie.dat
holds a history of the game so that the game can be replayed as a "movie".
BUGS
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.
AUTHORS
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.
COPYLEFT
Copyright (C) 1987, 1988 Chuck Simmons
See the file COPYING, distributed with empire, for restriction and warranty information.
NOTES
1. A Brief History of Empire
http://www.classicempire.com/history.html