The other side of reality

I finally got around to watching Stranger Things. After all the hype it came as a disappointment. I get that it's a pastiche of '80s movies, but I like my pastiches to be more than just familiar ingredients slung together and reheated. Nostalgia doesn't rule out putting something fresh in the mix. Think of Super 8, or even Fargo (season 1, obviously). Without the spark of originality, you might just as well be listening to greatest hits covered by a tribute band.

But I digress. I don't want to talk about 1980s, Stephen King, or pastiches in general. It's just that the Upside-Down in Stranger Things jogged my memory about a game concept I sketched out at Eidos in the mid-'90s. We needed a quick-n-dirty game (famous last words that have brought many a developer low, those) to show off Sam Kerbeck's cutting-edge 3D engine. It needed to be a realtime strategy game because that's what our game Plague, later renamed Warrior Kings, was. Sam happened to flip the landscape upside-down while showing off what it could do, and something in my brain put that together with the Aztec land of death.

We never got around to doing the game, as Eidos shut down internal development a few months later and Sam went off to do other things. His engine got used for another RTS game, Warzone 2100, but never in the freaky way I had in mind.

AZTECS

A variant on Plague set in pre-conquest Mexico, using the same engine and basic game design principles. It's anticipated that Plague will make quite a splash, and Aztecs will satisfy demand for follow-ups in the long wait for Plague 2.

Aztecs will however not be simply a copy of the original game swapped into a different setting. The Mesoamerican world is uniquely colourful. The architecture, costumes and imaginative mythology have rarely been used in computer games and merit a product that stands alone.

City management will be less intricate than Plague. This will be a game of warfare and keeping the gods happy.

All flesh is grass
Villages supply food. Food is not an explicit resource in the game as with Plague but is simply shared out to any units within range of your buildings. Rather than bothering with quantitative measures, you can tell how well the farms are doing by the landscape textures used: rich green if there's plenty of food, dusty scrubland if times are hard. Lack of food leads to loss of hit points; an excess is required for units to recover from injury.

As long as your people are healthy and well fed, new Aztec children continually appear in the School. You can pick these up and drop them onto other buildings, which will determine their fate in life. For example, a child dropped onto a Temple becomes a Priest, one dropped onto the War Lodge becomes a Soldier, etc.

Do it this way
Units are given orders through a (graphic) verb/adverb icon system. This means you can tell a unit to Attack (the verb) and just leave it at that, or you can go to the next level of icons to specify how the attack should be carried out: Aggressive, Balanced or Defensive (the adverbs). As with Plague, what you don't specify is left up to the individual unit's AI.

An eye in the sky
Your view is provided by a flying camera giving an eagle's-eye view of the world. You can fly the camera anywhere, but how much you get to see depends on whether you have any units nearby. Within range of a friendly unit, the camera can see enemy units and the condition of enemy farms and buildings. Outside this range the view enters the Fog of War; it becomes sepia-tinted, buildings appear stylized without hit point info, and enemy units freeze and gradually fade as if from a persistence of vision effect.

Trading in secrets
Merchants were notorious in the Aztec world for spying. This is reflected by allowing all players to have a clear view, free of the Fog of War, when within range of any player's Merchants. Thus the Merchant who increases your wealth by trading with another city will also allow you a clear view of that city's defences during his visit there but this advantage is a two-edged sword.

Discriminating views
View of enemy units is subjective. This reflects Aztec warfare, where experienced soldiers were needed to recognize details of enemy deployment. In the game, you can only distinguish the enemy's elite units (Eagle Lords, Jaguar Lords, Arrow Knights and Hummingbird Priests) if you have elite units of your own near at hand. Otherwise all the enemy's troops appear as generic soldiers and you won't know where the danger lies.

The flipside of reality
Slain units become Skeleton Warriors in the Underworld: a subterranean mirror-image of the living world, where mountains ridges become narrow defiles and vice versa. You view the Underworld by flipping the world around to see the underside. The Underworld is another front where you must fight wars, because the concentration of your Skeleton Warrior forces in the Underworld affects the power of your Wizards' magic in the world above. You have only very limited control of your Skeleton Warriors: you can order them to move, but once they get where they're going they'll just attack any other tribe's Skeleton Warriors that are nearby - even if the other tribe are your allies.

Open heart surgery
Morale is improved by human sacrifice, making it worth capturing foes and taking them back to your Temples. This also prevents the slain foes from becoming Skeleton Warriors in the Underworld, as well as earning you the favour of the gods. You can see this as a strengthening of the glowing aura around the shrine on top of the Temple, which is what your Priests draw on to cast their prayer-magic.

Visitors from heaven
Sometimes, when a Temple's aura is very strong, a Hero will emerge from inside it. These Heroes are beings sent by the god to aid you. They have special strengths in battle, magic, etc, depending on the god. (There are gods of Rain, War, Sun, Learning and Luck.) However, the main advantage of a Hero is that they can dreamwalk. This is essentially a way of setting up a long string of orders for the Hero to follow: a dream-self (Nahual) is created which you can run rapidly around the map, giving it a sequence of orders which it will remember. When the dreamwalk ends and the dream-self merges with the Hero's physical body, he carries out the orders you gave during the dreamwalk. This allows you to set up complex tactical patterns of attack and defence and hold them in readiness, waiting to awaken your Heroes at the moment of greatest need.

The nitty-gritty
There will be considerably fewer buildings and unit types than in Plague. The basic buildings featured in the game are:

• Palace School (spawns new units)
• Ball Court (increases public contentment)
• Skull Rack (each unit sacrificed adds a skull, boosting morale)
• Market Plaza (stimulates trade)
• Gladiator Platform (combatant is upgraded to veteran or killed)
• Wizards' Tower
• Priestly College
• War Lodge
• Temple (five types)
• Canal
• Well
• Road
• Causeway

Buildings concerned with resource production &/or processing:

• Farm (can be set to produce food or cash crop)
• Fishing village (produces canoes that can be seconded in wartime)
• Weaponsmith (upgrades swords, invents spearthrower)
• Cotton Mill (supplies cotton for armour)
• Quarry (supplies obsidian for swords and stone for buildings)
• Mine (supplies gold)
• Banner Maker (improves the commands you can issue to units)
• Aviary (supplies Banner Maker)

Resources that the player is told about in detail:

• Gold
• Stone
• Mana (decreases over time, but never below increasing limit based on total sacrifices)

Hidden resources that you have only qualitative control over:

• Food
• Cotton
• Obsidian

Basic unit types:

• Commoners
• Merchants
• Nobles
• Priests
• Wizards
• Scouts
• Swordsmen 
• Javelineers

And veteran units:

• Eagle Lords
• Jaguar Lords
• Arrow Knights
• Hummingbird Priests

Not all of those ideas would have made it into the finished game, of course. This is just a brainstorming pitch document to get the design process started. That's my favourite part of any project, incidentally, though I'm also willing enough to roll my sleeves up and keep toiling away to the finish line.

Breaking the butterfly

Last week I was talking about Plague, the game I designed at Eidos in the mid-90s that morphed from sim-medieval London to "the game of war, Black Death and taxes" to the unabashed RTS that was Warrior Kings.

I wish I had more than snippets from old documents to show you. Sam Kerbeck's 3D engine was amazing. He and lead artist Richard Fletcher worked 24-7 for weeks to build a demo that would make the execs at Eidos take notice. Unveiled at E3, that demo reportedly rattled Peter Molyneux enough to put Populous: The Beginning back by six months. The engine was whisked over to Eidos subsidiaries like Pumpkin to use for Warzone 2100, but development on Plague itself was dogged by the politics that comes of being located at a games publisher's head office. One day I'll write the novel, only nobody will believe it.

So this (below) is the second attempt at an intro for Plague. The idea of writing these was more to give the team a creative focus than to necessarily be the actual game intro, as by this stage development had entered a kind of reverse Zeno's Paradox whereby the projected shipping date seemed to be receding into the far future. Within another year I had seen that the only way to fix the whole thing was to junk Plague and start afresh with Warrior Kings. It worked for a little while, but - Oh, maybe I'll save that story for the novel too.

Plague Intro Movie

A glimmer in darkness. Words briefly appear on the screen: Sunset, on the Day of Judgement. The words fade.

There's the sound of screams and moans, of many people. Flames licking up out of the darkness around ruined towers. We're pulling back gradually as the flames die down and the screams recede away...

The fires fade and we continue pulling back. What seems to be the walls of an immense dark cavern reveals itself to be the socket of a skull. We continue pulling out. It's not a whole skull, the lower jaw's missing, and it's charred and blood spattered. We see a black clawed hand is holding it.

The hand crushes the skull. There comes a hideous gasp of triumph. Continuing still to pull back, we see (from low angle shot - he looks immense) a figure. Under his cowl, you can't quite make out his face - it could be black bone, or hard black beak like a raven's. He has black raven-wings and a scythe.

We stop tracking out with Death in three-quarter shot and pan across as he turns to survey a wasteland, shrouded in smoke or fog. Music: the "Dies Irae" from Symphonie Fantastique. The sun hangs on the horizon, strangely close. Death lets the last fragments of the skull fall.

DEATH: It is over. Mankind's day is done. The last mortal soul speeds on its way to Hell, and Death holds illimitable dominion over all.

Hold on the scene a moment. The music fades away.

There's a flare of white light from behind Death. A wind roars across the plain, dispersing the fog. We pan round as Death turns to see...

A figure all in white, delicate features, with jagged fractal wings like a marvellous butterfly. The wings may have caused the wind, but now they're relaxing slowly back into position as we see the figure. White light shines from behind him.

DEATH: I thought I had slain everything.

ANGEL: I am the last of my kind.

DEATH: You come too late. This is the end of Time. Eternity is drawing to a close.

ANGEL: Perhaps.

DEATH: There's nothing you can do for Man. He has been judged for his sins and sentenced to extinction.

ANGEL: Perhaps not.

DEATH: Who are you? Tell me what name to carve in the stone that shall press your corpse into the earth!

ANGEL: I am hope. While I live, Mankind has a future.

DEATH: While you live - ? I'll putrefy your body with a thousand pestilences, rack you with a thousand agonies... break you down to atoms and less than atoms and scatter the debris across the cosmic void.

While they've been talking we've tracked across towards the angel (the whole thing is one continuous shot all the way through with no cuts), who turns briefly to look into the sky. With the fog gone, a long swathe of dim stars is visible in the darkness. The angel reaches up and takes them from the sky - a sword made up of a million stars that flare with renewed light at his touch. As he turns back to face Death, his eyes and mouth glow with inner white light.

ANGEL (smiling): Want a bet..?

As they move together, the scene blurs and starts to fade, becoming a swirl of black and white that spirals around and around...

The game options are superimposed, set out on bars that mirror the Light vs Darkness theme (ie, hardship level, difficulty level, etc). The player selects his options...

The swirl, like a whirlpool, opens up to reveal the start of the game.

Plague outro 1: Dark Lord victory

The same desolate plain seen the start, now completely shrouded in a thick blanket of mist. Slowly a hump rises, like a black mushroom. Tracking in, we see it's a hunched figure in black robes: Death. Slowly he rises to his feet, the mist swirling around him in slow eddies as he moves, and the camera POV moves around likewise, ending close in and to one side of him.

DEATH: So that was Hope...

He swings his scythe round. A single tatter of white robe hangs from the tip of the blade.

Death plucks off the tattered fabric, gazes at it a moment. In his hand it blackens and shrivels.

DEATH: ...but now he too is gone. In all the universe, there is no living thing left...

Death suddenly looks straight at the camera. It's a bit of a jolt, seeing into his eyes for the first time. More of a jolt is the implication that we're actually present in the scene.

DEATH: ...except for you.

But does he mean it as an acknowledgement of victory, or something more ominous?

As he starts towards us, suddenly, cut to black.

Plague outro 2: Bright Angel victory

Death and the Angel are locked in combat, but Hope has the upper hand. Death falls back, and behind him a swirl of nascent stars forms in the dark void. The mist is sucked away into them - and the plain too, leaving Death and Hope suspended in a cosmos which is starting to glow with new nebulae.

Death's scythe is pulled out of his grasp, sucked back into the swirl of stars, which now begins to resemble a galaxy - setting the scale as cosmically huge.

Death braces himself against the cosmic wind. His robes flutter and snap, but the Angel is unmoved. Remorselessly he reaches out to place his hand around Death's black mask-like face.

DEATH: You can't destroy me! I am Death...

We cut to the Angel's face. With the brilliant light behind his eyes and mouth, he hardly looks human at all.

ANGEL: Not any more.

Cut back and pull away fast as he closes his grip. Death's head seems to shatter, and as it does there is a blinding burst of light as the Universe begins again.

Cut to a man's face, waking startled from a dream. He's a BEGGAR, wearing rags and sleeping in the gutter of a medieval town. From the angle and colour of the sunlight we guess it's dawn.

The beggar gasps and mops his brow, relieved that it was all a dream. Then a shadow falls across him and he looks up, momentarily alarmed. We see him shield his eyes, squinting into the sun.

BEGGAR: Who are you..?

Cut to the beggar's POV, looking up at a STRANGER who is silhouetted against the rising sun so that we can hardly see his face because of the halo of light.

STRANGER: Do not be alarmed. I'm not here to hurt you.

BEGGAR: Stay away for your own sake. Do you not see I have the plague?

The stranger bends to help him up, and as he does we cut back to the beggar's face. Before he may indeed have been pockmarked, but now there are no sores on him.

STRANGER: The plague has gone. You do not have it.

The stranger steps back out of shot. The beggar gets up, feeling his face in growing amazement as he realises it's true, he's been cured.

He looks up for the stranger, then we see him look puzzled because the stranger has gone. He looks around.

Cut to see the stranger walking off down the narrow medieval street, trailing his fingers past beggars who are waking up to a new day. There's astonishment and delight as each realises that he too is free of the plague.

As the sun rises higher, there comes the sound of birdsong and the growing bustle of the town. The beggar watches till the stranger is out of sight, then notices something in front of him. He bends down and plucks it: a beautiful flower coloured like a butterfly's wing.

I do remember showing it to Ian Livingstone and he thought the intro script would be better if, after the Angel says, "Want a bet?" Death curls his (unseen) lip and purrs, "Oh really...?" I tend to think one punchline is enough, but that's the problem with being a writer. Everybody thinks they can do your job. There was also an Eidos game called Gangsters. The copy for the poster read: "Real power is never given..." with an image of a wild-eyed wiseguy with a tommy gun spitting lead. The Eidos brass added a line at the bottom of the poster: "...It's taken " - just in case you hadn't got the point. Two punchlines again, you see. May Death and the Angel of Life both save us from execs with too much time on their hands.

Red planet and red braces

Last year I ran a post about Thirst, an RTS game concept set on the kind of prehistoric Mars that used to be as familiar as the back garden to readers of Planet Stories. I planned to work on it with Sam Kerbeck, Martin McKenna and some other ex-Eidos developers - until the dotcom bubble burst and 9/11 shocked us all, and between those events investors quaked in their socks and ran and hid.
What I forgot when I wrote the original post was that the pitch for the game got a wee bit further than my 'flu-induced intro storyboard and some design notes on the back of an envelope. Martin worked it all up into quite a nice presentation, as you can see from the sample slides here. And it wasn't just eye candy either: Sam's incredible 3D graphics engine proved how good the finished product could look on PC screens.
Trouble was, the venture capital offices around London by then looked like Escape from New York. In one company, called Nuclear Melon or Fuchsia Clementine or something (I kid you not, they grew up listening to pomp rock, those VCs) I swear I felt broken glass crunching underfoot. There was a whimper from under one of the desks, the kind of sound a man only makes when he's seen his stock options plummet by more than the GDP of an emerging nation. Yet the traumatized VCs calmed down when they heard our pitch; one fellow fluttered his pink tie and, I think, even smiled in a timid way. Had we thought to take doughnuts we might have enticed them out and got our startup funding even then. But no. So Mars remained arid, gamers moved on, Britain's welfare state buckled a little more, and investors throughout the land had to slum it for a few months without the comfort of a third home in the Algarve.

Fever dream

Just when I think I've run out of utterly obscure curiosities to dust off and show you, I go and open a box in the attic and find a dozen more. This time it's a top-level design concept for a browser-based 3D realtime strategy game. This would have been written back around 2000. Having just left Eidos along with Plague lead coder and Warzone 2100 engine creator Sam Kerbeck, the two of us we were looking for a project to work on together.

I got the 'flu and had this weird dream about a guy searching in the dust of Mars a million years ago for the last drops of water. When I woke up, I wrote it down exactly as I saw it and then started sketching out the combined arms principles of the game.

The aim was to make a very simple little game with not too many units, all of which would be low-poly models, so that we could get it done quickly and cheaply. (Yeah yeah, you should always laugh when somebody says that about an RTS.) Then we got more ambitious - as we always do - and decided to turn it into a much bigger game using the astonishing graphics engine Sam created to replace the one for Plague, later Warrior Kings, which was "based on a concept by Ian Livingstone", as the saying goes, insofar as the actual concept in question was for a turn-based 2D version of SimCity set in 14th century London. I kid you not.

Anyway, this game was based on a concept by my virus-cooked subconscious. In my dream it was called Liquid, and I envisaged the ad in Edge with three coloured dots beside an image of Mars, labelled as follows:

Water - the colour of Life
Poison - the colour of Death
Blood - the colour of War

Yes, I know - a bit rough-edged to say the least. But to come up with this stuff while you're asleep and running a temperature... Well, you try it. And I believe it is always worth taking the raw material that you get that way and seeing if you can make something good out of it, because it is the one and only time you're creating without the nagging whisper of your critical faculties.

First thing to go would have been the title. It was about the desperate struggle for resources. Thirst seemed to fit it better - and that's a name I've always liked.

What happened? The dotcom bubble happened. We should have stuck with the quick-n-dirty version, because after the shit hit the FTSE there wasn't nobody handing out a million or two for a start-up game developer. But here is the original fever-fuelled outline:

The red desert of Mars. A fissure in the ground. Our view descends into a crevice, down and down towards the sound of running water. A skin of water ripples down the walls, which are covered in astonishing patterns of phosphoric salts. Further down, far below the planet's surface now, the water runs into a gushing underground river. The river is bubbling, pounding, frothing... A living force in the heart of the dry rock.

The pressure builds, sending a jet of water up the crevice. Back on the surface, the dry edges of the fissure moisten with droplets of water bubbling up out of the interior of the planet. It seeps out into the dusty red sand –

A man wakes. His grey eyes stare in shock, fatigue, despair. His blond hair is plastered with sweat. He is wearing a white environment suit and a mask across his mouth and nose.

The image of bubbling water must have been only in his dreams, as all around him lies a desolate dry landscape: ochre-coloured dunes tinted with patches of olive lichen, red sandstone boulders like giant fossilized eggs. Huge flat-topped mesas stand out darkly against a cobalt blue sky. The sun is smaller, dimmer than it appears from Earth, and there are two swift moons.

The man stands and takes a flask from his belt. Removing his mask, he lifts the flask to drink. But there are only a few drops left. Barely enough to wet his cracked lips. He throws the flask down at his feet.

There is a rhythmic hum on the air. As the man looks around trying to work out where it's coming from, his eyes fall on the shadow at his feet. It is cast by the mesa behind him.

So why is the shadow moving?

The man stands with the mesa behind him outlined against the sky. As he turns his head, an airship prow emerges over the edge of the mesa. Slowly it drifts overhead, filling the sky. There is a hieroglyph on the side of the airship - not the same one that is on the man's suit. He grabs his harpoon rifle but it's obvious that it would be futile for one man to attack such a vast ship. As he watches, ports open in the sides of the cabin slung below the balloon. Green droplets are ejected and fall in slow motion towards him.

He's frozen for a moment watching the green droplets fall. Then he runs. Behind him, the poison bombs splash against the red dust - splattering heavily, they contain dozens of gallons each. There is an acidic hiss and clouds of green vapour start to spread. The man pulls goggles down to cover his eyes.

He rounds the mesa. Reflected in his goggles is a horde of giant crustacean – or insects, maybe. Their hard limbs make a thunderous chittering on the rocks as they march towards his location. Carried in their mandibles are the creatures' riders: soldiers in black environment suits. There are hundreds of them.

The man looks back. The airship has manoeuvred into position between two mesas and is continuing to bombard the ground with poison charges. As he stands undecided, an electrical blast from the vanguard of the insect riders catches him a glancing blow and spins him around, sending him sprawling in the dust.

He's lost his rifle. His arm is stiff where the electrical bolt hit. Maybe he blacked out for a few seconds. With desperate bone-weary strength, he pulls himself to the foot of the mesa. Sheer luck guides him to a cave, the entrance partly concealed behind a jagged rock. He crawls inside, his feet tumbling over the pebbles. He disappears just moments before the insect riders come into view.

He peers out. There is a haze of dust as the riders mill to and fro, the huge insects gleaming like oiled machinery. At close range the insects look like scorpions, their heads tiny in comparison to their massive chitinous bodies. The riders sit in massive jaws that protect them like a cage, while above them gleam the insect's inscrutable jewelled eyes.

The airship has dropped anchors. They are tethering it between the mesas, lowering a ladder so that the crew can descend to the camp.

The man retreats deeper into the cave. As the noise of the soldiers outside grows fainter, he hears a trickling sound. He looks at the wall of the cave. Something odd. The rock seems to quiver and swim...

He reaches out and touches the wall. Water flows around his fingers. Tentatively he touches it to his lips - then he is splashing it over his face and pressing his face against the rock to drink.

Half crazy with the discovery, he runs back up the passage towards the mouth of the cave. But a rider of the enemy army is there, his insect mount stooping to allow him to look into the cave. As he sees the man, he levels his gun. The man cries out in panic, pointing back into the cave. He's trying to tell them about the water.

Too late. A blast of electricity burns through the air, flinging the man back. The last sight we see is the liquid gleam of his eyes as they go dull and dead.

GAMEPLAY

Units

Ground units:

Infantryman - Carries a polearm with a white-hot welding-type arc at the end. Very tough in close combat. Medium armour.

Plasma Artillery - Carries a heavy bazooka that fires plasma blasts. When artilleryman is in position, bazooka takes a few moments to set up on its base before it can fire. Weak in close combat, because they cannot fire at point-blank range (the plasma blasts have a detonation radius). Medium armour.

Kelid Riders - Humans riding in the jaws of giant scorpion-like insects. They fight with magnetic guns that fire thin metal harpoons. Light armour.

Aerial units:

Airship - Huge hydrogen-filled balloon driven by solar-powered propellers (the solar panels cover the balloon surface). At manoeuvring altitude, the Airship moves a little slower than an Infantryman. At cruising altitude (higher) the Airship enters the Martian jet streams and potentially can move faster than any other unit, but only in the direction of the jet stream - in order to switch to another jet stream in a different direction, it must first drop to manoeuvring altitude. (Note: the directions of the jet streams are very predictable, like rivers, but their speed changes slightly with the seasons.) Airship weaponry consists of bombs that explode into clouds of acidic gas when dropped - Infantry and Artillery will die before they can get out of a direct hit, but Riders are fast enough to escape the cloud with only about 50% damage.

Skimmer - A very fast, low-flying intelligent creature like a dragonfly. Skimmers live in hives in the caves inside a mesa and will collect ore, which they deposit at the nearest friendly Command Post. As aerial units, Skimmers can see further than troops on the ground and this means they also act as an early warning system of attacks on their city. However, they are not intelligent enough to distinguish troops' type or allegiance - to a Skimmer, they just appear as generic units.

Armour Weapon Range Move
Infantry 3 7 1 5
Artillery 3 6 9 4
Rider 1 3 8 7
Airship 2 9 - 4/6-8
Skimmer 0 0 0 9
(For comparison, mesas are about height 6-7 and Airships fly at heights 9-20.)

BUILDINGS

All buildings except Bridges must be placed on top of mesas. They are built by Infantry, using the arc-welding effect of their lances.

Bridge - A means of spanning the gap between mesas to extend a city. Energy can be carried along the Bridge's cables, allowing a network of mesas to draw off a shared set of Pylons. Troops can cross bridges, and Fulmin Turrets can be placed on them. Force bubbles do not protect bridges, however. Bridges can also be built across chasms.

Command Post - Generates a force bubble that covers the top of the mesa. The strength of the bubble depends on the energy available. Force bubbles can only be destroyed by Artillery. All types of ground troops can be spawned at a Command Post.

Fulmin Turret - Has a ranged electrical-blast attack that is effective against all units (weapon strength 8 if Turret fully powered, range 7).

Hydroponic Farm - Must be built on the edge of a mesa. Pipes lead down the side and into the ground at the base of the mesa, extracting water from the deep wells below the planet's surface.

Hangar - Used to spawn Airships.

Pylon - A high metal tower stretching up into the jet stream. This continually attracts an electrical halo, generating Energy.

RESOURCES

Energy - generated continually by pylons and fed to all buildings within that city. Energy is used to power Fulmin Turrets and a Command Post's force field - these continually draw energy, and if not enough Energy is available they are weakened. Spawning new units also drains energy. Since space on top of a mesa is limited, you have to balance Pylons for Energy production against other buildings.

Ore - available scattered across the surface of Mars. Some areas are particularly rich in Ore. Meteorites sometimes fall from space, creating a new source. Ore is usually collected by Skimmers, but can also be picked up by Infantrymen, who use their arclite lances to break down the ore. (Infantrymen given the order to gather Ore move at reduced speed until they can return to the Command Post or are ordered to drop the ore.)

Water - an "implied" resource, like food in Warcraft. You don't have to collect and store water, you just build Hydroponic Farms and that sets your population limit.

COMBAT PARADIGMS

It's possible to describe typical combat results, assuming equal numbers on both sides. These paradigms can be changed by other factors such as terrain.

Infantry vs Artillery
Infantry will take some damage but will catch up to Artillery (who move a bit slower because of their heavy guns). In close combat, the Infantry then win easily. (Note: the Infantry will take greater damage if advancing in close formation, because of the detonation radius of the plasma bolts.)

Infantry vs Riders
The Riders can back away (the insects go equally fast in all directions, and are swifter than men on foot) while firing. The guns don't do a lot of damage, but they will slowly whittle the Infantry away. So the Riders win with no damage to themselves.

Artillery vs Riders
The Artillery's plasma blasts do more damage than the Rider's guns. A further problem is that an insect taking a direct hit will scuttle burning through the ranks, causing confusion. Artillery wins, but will sustain about 50% damage.

Infantry vs Airship
The Infantry can do nothing.

Artillery vs Airship
Artillery's range is unaffected by the direction in which they shoot - even straight up. Assuming the Artillery start firing as soon as the Airship is in range, a sufficient number should be able to destroy it before it is in place to drop bombs. (Note: this is not a literal 1-on-1 paradigm, as one Airship costs as much as maybe six Artillery.)

Riders vs Airship
The Riders can do some damage to the Airship, but their guns are affected by the altitude they are firing at, so it's minimal. If the Riders stay in position, the Airship will bomb them before it has taken much damage.

TACTICAL & ENVIRONMENTAL PLOYS

Sandstorms reduce the effectiveness of ranged units (Riders especially).

Riders shooting downhill get a damage bonus that can turn the tables against Artillery (whose weapons do the same damage whether shooting up or down).

Riders who can get close enough to ambush Artillery (eg, by hiding in sand dunes or behind a mesa) will beat them because the Artillery cannot fire at point-blank range.

Infantry who can trap Riders (eg, in a narrow pass between two mesas) will be able to slaughter them easily, as the Riders cannot then retreat while shooting.

Riders who are on a mesa can do more damage to Airships (because there is less of a difference in altitude).

ORDERS

Rout - Units drop their weapons and flee back to nearest friendly base. You have to re-equip them, but at least you save the men.

It's rather strange to come across this after an interval of ten years, especially given the atypical inception of the concept. It's a never-was project, of course. You get through a lot of those in the videogames industry - which is the main reason why I returned to writing.