The Armageddon Man

01 · The game

Supreme Commander for a year

A strategy game played entirely through one screen of icons, in which the player answers memos and letters while the world drifts towards war.

The player is Supreme Commander of the United Nations of Nations, the U.N.N., in a world split into sixteen member countries with nuclear missiles. Each country has its own resources, missiles and temper. Every few seconds one of them does something to another: a trade pact, a car bomb, a missile attack. A memo reports it, and the player answers Neutral, Support, Criticise or Ask for Talks. Each answer changes how much each country trusts the Commander and how much the two countries hate each other.

Between memos the player reads the IN tray, sends standard letters from the OUT tray, moves the U.N.N. Force, puts satellites in orbit over the map and listens to the radio. The year lasts 52 weeks. It can end sooner: when a country gets the Commander recalled, or when the world's radiation reaches the top of its scale.

02 · The main screen

A Spectrum screen inside a Commodore 64 one

The game came from the ZX Spectrum, and the C64 version draws everything inside the Spectrum's 256 by 192 pixels.

The C64's memory is a row of 65,536 bytes, each a number from 0 to 255. Numbers that start with a $ are hexadecimal, and those in dark boxes are addresses in that memory, or the names the listing gives them: each opens the Source code tab at that point.

The screen is a high-resolution bitmap, a picture of 320 by 200 dots stored a bit a dot, with a pair of colours for each 8 by 8 cell. The game uses only the 32 by 24 cells that start at column 4 and row 1, the size of the Spectrum's screen, and leaves a striped frame around them. Its table of row addresses, screen_rows ($4FD3), starts at that corner, and a leftover routine for placing sprites, unused_sprite_at ($51C9), still takes Spectrum coordinates and adds the C64's border.

Two colour fills make the picture. At start-up every cell gets $1E, white on light blue, which colours the stripes and icons. Then fill_cells ($717E) paints the map's 21 by 14 cells $D0, light green land on black sea, from the five bytes that follow its call at $7C5C. The arrow is two sprites, the small pictures the video chip moves over the screen by itself: a white outline over a black solid shape, so it shows on any colour.

Each country owns a rectangle on the map, the first four bytes of its record at countries ($5DA4). The rectangles are what the satellites look for, and they do not follow the coastlines: the Eastern Block's is 71 pixels wide and Israel's 3.

03 · The music

Music: one tune for the whole year

The tune starts on the options panel and plays without a break for as long as the game runs. Three more tunes and seventeen sound effects sit beside it, and nothing ever starts them.

The driver plays three voices from patterns of notes and commands: arpeggio tables, vibrato, slides, a glide from note to note and drums made of a burst of noise on every other frame. Each tune has a speed, the number of calls between steps of its patterns (tune_table, $46E3). The raster interrupt calls the driver once a frame, but sound_irq skips one call in ten, so the music gets 45 calls a second rather than 50.

Tune 0, at speed 6, is the music the manual credits to Millers. Tunes 1 and 2, at speed 8, and tune 3, at speed 5, are jingles a few seconds long. Nothing in the game starts them, and the sound effects are just as silent (below).

04 · The sound effects

Sound: seventeen effects the game never plays

A player for two-voice sound effects and an alarm sits in the sound code, ready to call, and no instruction in the game calls it.

Each effect is a record of twenty bytes, from sfx_0 ($4B39) on, found through sfx_table ($4B17): a frequency, an envelope (how the volume rises and dies away), a waveform and a pulse width for voices 1 and 3, a step that sweeps each frequency up or down, how many steps the effect lasts, and how often and how many times it goes back to its starting pitches. While an effect plays, the music gives up voices 1 and 3 and keeps voice 2. The alarm takes voice 2 instead: a steady tone with the period 7, noise with the period 0, and a tone broken by bursts of noise with any period between.

No instruction calls sfx_start or alarm_start, and no table holds their addresses. The effects, the alarm and their records fill $4A48 to $4DB0, 873 bytes, and what the game would have played them for is not known.

05 · The clock

A week lasts 31 seconds

The world moves on a clock that counts frames on the main screen, and it stops while a window waits for the player.

The main loop makes one pass a frame, so a tick is 192 frames, 3.8 seconds on a European (PAL) machine. Every tick one country may act on another (next). Every fourth tick the radio may pick up a message, and on the tick after it a Big Bird satellite may report. Every eighth tick ends the week, and a week of 1,536 frames lasts about 31 seconds. A year of 52 weeks is 27 minutes of the main screen, and much longer in practice, because the clock is the main loop's: a window that waits for an answer holds the whole world still.

06 · How a country acts

Each country climbs a ladder of 32 events

On every tick the game picks a country at random and looks for a neighbour whose hostility lands on one of the country's 32 event levels.

The game keeps a table of 256 hostilities at relations ($5C5C): how much each country dislikes each of the others, from 0, the friendliest, to 255. Each country also has a ladder of 32 levels, one for each event it can start, from a Total Missile Attack at 255 down to a Mutual Defence Pact, between 4 and 40. A level of 0 means the country never starts that event: Canada never assassinates a diplomat.

On each tick country_events picks a country A at random, skipping one that has been destroyed. It then goes through the other countries from a random one on, and for each it compares A's hostility to that country with A's ladder from the top. The first level within one of the hostility wins, and its event happens. A country with no match anywhere grows more hostile to everyone by one, and every country grows more hostile to every other by one at the end of each week, so a world left alone drifts up its ladders towards war.

The ladders have gaps. Most of the rungs are 7 to 9 apart, and a level matches only a hostility within one of it, so most hostilities start nothing and the drift carries them on to the next rung. One comparison goes wrong. The difference is read as a signed byte, a number from -128 to 127 in which 255 stands for -1, so a hostility of 0 lands one away from 255, the Total Missile Attack. Two countries at the friendliest possible relationship destroy each other.

07 · The answers

Every answer moves trust and hostility

The player's only levers on the world are the answers to memos and mail, and the letters in the OUT tray.

Each event runs a script in the game's own little language, which the engine at script_commands ($4EB3) reads a command at a time. Most events show a memo with four answers, and each answer is a script of its own. The answers raise and lower each country's confidence in the Commander, byte 9 of its record, from 0 to 255 and 128 at the start, and push the two countries' hostility up or settle it down to a calmer rung of their ladders. Many post mail that arrives this week or later, and mail left unread at the week's end runs a follow-up script instead, most of which cost trust or raise hostility. Answering Neutral to an assassination, a mobbed embassy, a car bomb or aid to an opposition is the most dangerous answer in the game: half the time it ends the game.

Before most events a country may make a demand. A country at least as strong in missiles as its target, and short of natural resources or technology, demands ten units of what it lacks. Yes hands over one unit and the event is called off. No lets it happen. Ignore makes both countries as hostile as the next harsher event on the ladder, and runs that one instead.

The letters work through trust. Most of them roll a random byte against the country's confidence in the Commander, and do what they ask only when the roll comes in, unless the U.N.N. Force stands on that country's soil.

08 · The satellites

A satellite sees a few pixels around it

Six laser satellites shoot down missiles and three Big Birds spy on countries, but only on a country whose rectangle comes within five pixels.

A satellite is placed from the satellite panel: the cursor carries it to the map and fire puts it in orbit, a dot of two by two pixels. Its record (satellites, $5D5C) keeps its position and a reach of 5 in each direction. The test in_cover ($C0AC) asks whether the satellite's x lies from 4 pixels left of a country's rectangle to 5 pixels right of its last column, and its y the same way. The rectangles are small, so a satellite covers one country, or two or three where they crowd together around Israel.

Each frame a missile flies, every laser satellite in orbit has a 1 in 4 chance of trying for it, and catches it when the missile is under the satellite by the same test. A Big Bird does not catch anything. Every fourth tick, one after the radio, it may report a country beneath it, and the eye in the satellite panel lists what each kind covers. With no Big Bird over a country the eye says "No Foot prints!", even when the laser satellites cover half the map.

09 · The radio

Eight filters unscramble a message

A message picked up while the radio scans arrives scrambled, and each of eight filters set right lets more of it through.

Each country transmits in one of six bands, from 1,800 to 50,000 kHz (country_bands, $7C31), and every fourth tick the game may pick up a message from a country on the radio's band. While the radio scans, the message is shown under eight filters, f0 to f7, each a bit of a byte the player sets by clicking. Each country has its own key, one byte in scramble_keys ($7C41).

Every message starts with RYRYRY, the line of R and Y that teleprinter operators sent to test a link, before the text itself.

The scrambling counts the bits where the filters agree with the key. With all eight right the text comes through whole. Otherwise each character survives when a random byte falls below 32 times the number that agree, and is replaced by a random space, digit or sign when it does not. So each filter set right lets another eighth of the message through, and with none right the screen fills with noise. A message picked up while the radio is stopped uses the key $00, which the filters match as they start, so it arrives clear.

10 · War

Every missile that lands is one hit

A Total Missile Attack starts an exchange in which each side fires everything the other can still take.

Each country's starting resources, technology, missiles and the hits that destroy it, from countries_table ($A9AD), six bytes a country. Resources and technology are shown in the game times ten, as percentages.

Each country holds three types of missile, MX1, MX2 and MX3. In a war, country A fires at B as many missiles as B can still take before it is destroyed, MX1 first, and B fires back as many as A can take, from its own stock (script_exchange, $C70A). The manual gives the three types different warheads and fallout, but in the code they differ only in the order they are fired: each one that lands is one hit and adds to the radiation by the same chance (war_damage, $CC10).

Missiles fly across the map a pixel a frame from three launchers on each side. A hit raises the target's count of hits taken, and the hit that reaches its limit destroys it: its resources and technology fall to 0, and the clock never picks it for an event again. Every other hit raises the world's radiation by one, by a 1 in 4 chance. The launchers have a fault of their own, which fires more missiles than the countries hold.

11 · The communique

Your rating is the world's trust added up

Every week ends with the U.N.N. Council's communique: a word for the Commander's performance and a word for the radiation.

The rating is the sixteen countries' confidence in the Commander added up and divided by 512, which gives 0 to 7 (week_end, $BAA1). Every country starts at 128, a total of 2,048, so a new Commander is rated Acceptable, the fifth of the eight words. The radiation, 0 to 255, is divided by 32 for its word, and a world with no radiation at all reads "Background." instead.

12 · The endings

Four ways the year ends

The game has four last messages (game_over_texts, $B428), and after each it starts a new year.

The year ends after 52 weeks with a rating of 16 less the countries destroyed, times 25, divided by 4 (year_over, $B36F): 100 with every country standing, 93 with one gone, and nothing at all for the trust the Commander built. The world ends at the end of a week whose radiation has reached 255. The Commander is recalled for lack of confidence by answering Agree when a country asks for a new Commander, and for incompetence by a Neutral answer to terrorism.