OSR: The Flame Pomerium (How to Run a Giant Mecha OSR Game)

Back in this post, I proposed that giant mecha fights could be easily run in most D&D-like games without changing any of the rules. All you need to do is change the scale.

Mortal Scale: the usual human scale.
Bulwark Scale: the giant mecha scale. 50x larger, but none of the values change.

I then tested the theory on the GLOG, on Lamentations of the Flame Princess, and on D&D 5th Edition, with varying degrees of success.

Since the mechanical side of things seems to be sorted out, here are my system-less notes on actually running a game using this method.

Group Structure

1. One Bulwark, Multiple PCs
The classic "starship" layout. One PC drives, one PC operates the guns, etc.
Pros: group cohesion, investment in common welfare.
Cons: "we've already fired the wand-cannon so you get to do nothing for the rest of the fight."

2. Multiple Mechas, One Per PC
The classic "group of high school kids save the world in an animated TV show" layout.
Pros: customized mechas, more feel of control, no one is left "idle".
Cons: less group cohesion, multiple mechas can solve problems more easily, more repair time.

3. Multiple Mechas, One Per PC, NPC crew
The classic "starship" layout, but with NPCs in most roles.
Pros: customized mechas, team uniforms, rivalries, and internal politics
Cons: more for the GM to track, traits can be diluted or flanderized by the squad structure

I prefer Option 3. For the rest of this post, I'm going to assume that's the default.

Scale and Features

-Bulwarks are mostly humanoid.
-In my mind, they are huge. 200-300' tall. Taller than a cathedral, taller than the Colossus of Rhodes. You can scale them up or down, and adjust the 50x conversion factor as needed.
-The things they were built to fight are bigger.
-Bulwark combat rounds are 1:1 with mortal combat rounds if Bulwarks in your game are between Evangelion speed and Pacific Rim speed. If your Bulwarks are slow and ponderous, a 1:6 or 1:10 ratio would also work.

Animation Budget vs Writing Budget

A lot of movies or shows with "giant robots fight things" start off in the same way. 
1. Evil monsters show up
2. Giant robots are built, fight them
3. More evil monster show up
4. More fights
5. Aaaaand then... beach episode? High school drama? Turns out it was all a dream? The very nature of reality is falling apart? The giant robot is powered by your mother or mashed kittens or, I don't know, the toenail clippings of a god? Things go sideways.

People very quickly figured out that, while your audience might say they want to watch a show about giant robot fights, you can only produce so much content before the well runs dry. Spectacle fights get kind of... boring after a while. Is anyone actually watching the fight choreography in most Marvel films these days? How much of professional wrestling, a genre ostensibly all about fighting, is fluff, backstory, drama, and entrance music?

The 40k Deathwatch RPG has this problem. The core loop is "Go on Missions -> Fight Aliens -> Spend Renown -> Get Better Items -> Go On More Difficult Missions". It's very difficult to do a highly skill-based combat system in an RPG without bogging down the entire game in rules. There are video games that are entirely about fighting and they work just fine, but in a tabletop RPG, you need something else. Deathwatch could have had an series of books to help you roleplay genetically-altered perpetual child-soldiers with god complexes and mythical backstories, but instead, more guns, more monsters, and more combat.

Spend your descriptive powers on the giant mecha fights, but spend your story-crafting, plot-hook-baiting, motivation-steering cunning on the human-scale plot.
The Old God of the Northern Mountains, Bjarke Pedersen

Bulwark-Scale Descriptions

Focus on the weight and scale.

Walking Events
1. A herd of sheep, in a blind panic, smashes a fence and flees across a broad plain, while their shepherd stands awestruck.
2. A flock of birds flutters past at knee-height.
3. Each step punches a pond into existence.
4. A row of trees bends next to your path, their roots shaken at your step.
5. You cross a stream in a single step, the wooden bridge creaking as you compress one of the banks.
6. Soil from your foot rains down with a gentle hiss, coating the land behind you.
7. A low cloud collides with your Bulkwark's shoulder and passes by, undamaged.
8. Ripples spread in the grass before you.
9. Flocks of ravens, drawn to your step, begin to congregate, hoping for a feast.
10. Your step causes a small landslide on a nearby hill or mountain.

Villages and Towns
1. Put shutters on their windows and sharpened logs all around their walls.
2. The old town abandoned; the new one buried into a rocky hillside.
3. Houses on carts, retreating towards the city.
4. A false-town, filled with meat and grain, to draw away the Great Beasts.
5. A festival of thanksgiving as you pass. Garlands of flowers wrapped around your feet.
6. Waving banners, in time to the heartbeat-step of your progress.
7. Music, played as loudly as possible, from the rooftops.
8. The bells in the church tower ring with each step, and tiles fall from the roof.
9. On a nearby hill, villagers build an effigy from sticks and cloth.
10. An open-air church service as you pass, the priest's arms waving in the air.

Every hit that deals 6 or more damage knocks a Bulwark-scale combatant 250' backwards, sideways, into the air, etc. This doesn't deal any extra damage, but it does allow for truly gigantic fights, positional play, and a chance to run away.

You Hit It
1. The attack drives the Great Beast to the ground. You lean over, pummeling its back with your weapon.
2. Your blow sends the creature flying through the air. An entire forest vanishes where it lands. It rises, shedding trees and roots, picking entire oaks from its flesh like splinters.
3. You stagger forward, pushing your shoulder into the Beast, then shove it backwards. Its claws for purchase in the soil, tearing new furrows in the fields.
4. You blow carries past the Beast and strikes the river. For a moment, the river's flow is stopped as waves travel in both directions.
5. One strike turns the Beast to your left, but the second strike knocks it to the right, sending it tumbling into a nearby hill.
6. You turn the Beast's attack against it, allowing its charge to glance off you and carry it, scrambling and flailing, into the ground.

It Hits You
1. You fly backwards, entirely off the ground for a few moments, but you land on your feet. You dig your weapon into the ground for balance, crushing a small barn.
2. You are knocked to your knees, sending a shockwave through the fields.
3. The blow spins you halfway around. You nearly lose hold of your weapon as it digs a furrow into the ground.
4. The Beast's charge knocks you flat on your back, an entire field away from where you were standing. It circles, waiting for you to rise before striking again.
5. You plant your foot, but the stone wall beneath your feet crumbles. You slip, and the Beast, seeing an opportunity, knocks you backwards.
6. You demolish an entire windmill or castle as you fall.

A 250' grid over real terrain.

NPC Crew

Generate these guys like standard hirelings, but alter them to suit the game and the Bulwark. Lean heavily on tropes. Mix and match as needed. Your Bulwark might have a crew of 10 or more, or it might be operated by a sole pilot. At the very least, even if your Bulwark is solo-crewed, you'll have a support staff at base. 3 NPCs per PC seems like a sensible ratio.

If the PC is young and bright-eyed:
1. A grizzled veteran, offers sage advice, dies tragically at a really inconvenient time.
2. A young but oblivious love interest, who only has eyes for...
3. A rival to the PC (better looking, richer, nicer teeth, smoother) but who is also (at face value) friendly. Not a bully, but just as infuriating.
4. A childhood friend
If the PC is old and experienced:
1. A young helper who reminds them of the good old days. Might die tragically. Will nearly die tragically a lot.
2. An old flame
3, A survivor from the War
4. A rascally dog

If the PC is morally ambiguous:
1. An allied rake to tempt them down the path of depravity. Meets a sticky but morally enlightening end by their own incompetence or something.
2. A moral guardian sent by a higher power, strict but caring, exposes flaws the PC never knew they had
3. A robustly innocent person, too dense to be tricked into anything, too good-hearted to torment
4. A rascally urchin

If the PC is morally upright:
1. A rebellious youth looking for a mentor
3. A real snake-in-the-grass spy-type character, whose motivations are always suspected, but who never acts overtly against the PC
3. A louche but incredibly competent assistant
4. Someone who is always getting up to bedroom hi-jinks with other peoples spouses, daughters, farm animals, etc. 

If the PC is from Foreign Parts or is another kind of outsider:
1. Someone else from Foreign Parts, on another PC's team, but from a rival tribe/family/clan/religious sect.
2. A genial oaf who represents the worst of local manner, or a fop who serves the same role
3. An obvious spy from the Monarch, here to ensure the PC stays in line
4. A local unwillingly assigned to the role of assistant and tour guide who gradually warms to the PC

If the PC is from Around Here:
1. A disreputable character from Foreign Parts, the only one capable of operating the Gnosis Engine or the Thaumaturgic Ray
2. A younger sibling who looks up to the PC
3. A parent who worked on the Bulwark and knows its secret inner mechanisms
4. A spy from another nation, pretending to be a spy from this nation

Stranger Structures:
1. The PC's Bulwark is operated and maintained entirely by one rambunctious family. Possibly all women; the men died in the War.
2. The Bulwark is crewed by a group of wizarding students. The PC has been elected Dean-Captain. The students are, as usual, drunk, rambunctious, lecherous, idiotic, and high-spirited.
3. A bunch of cloned Elves. Triplets or more. Weird, androgynous, etc.
4. The Bulwark is a living creature, either grown from the PC's flesh, or fused with their body.
5. The Bulwark is a chaotic, strung-together thing, crewed by pirates and reprobates.
6. Intelligent golems maintain the Bulwark. They have personalities and goals.

Bulwark-Scale NPCs

Too weird to adapt to player characters, too cool not to include.
1. Dungeon Bulwark. Stats as a Lich. All shall cower! All shall fear! Its eyes are Beholders. Its breath, a swarm of stirges! Its bones are tombstones, its muscles are chains! Its pilot is an insane but patriotic lich.
2. Dragon Ally. Stats as an iguana or crocodile that can fly, with a 1d6 breath weapon.
3. Gigantic Tentacle Monster from the Local Lake. A legend. Stats as a thrown poisoned dagger. Toss it at the approaching Great Beast.
4. Giant Golem. No need for those annoying Bulwark pilots now! The giant golem will be completely obedient, free of fear and... oh no! It's loose! How could we have foreseen this?
5. The Mountain That Walks. Stats as an Earth Elemental, property damage as a meteor strike. Changes geography forever.
6. Serpents of the Earth. Vast primordial snakes. Stats as snakes. They're kind of cute from way up here. Not so much at ground level.
Bamiyan Buddha, Afghanistan. Destroyed 2001.

Extra Ideas

Didn't fit anywhere else.

1. A shadow council directs the Bulwarks. Masked representatives of 10 different nations, unable to unite publicly.
2. Hangars carved into a mountainside. Entire villages surround each Bulwark.
3. A magic chainsword. Each tooth is a mortal-scale magic weapon.
4. Blinded pilgrims, hauling a spells-croll canister across the desert, ready to load its deadly contents into a Bulwark.
5. A gatling wand-cannon, each wand carved from a wizard-treant.
6. Allied rocs act as scouts, carrying war-boats full of cartographers.

Battle Ideas

1. Something to Protect (a village, a town, a city, a caravan, a downed Bulwark)
2. Surprise! There Are Two Of Them (ambush from above or below, a trap)
3. A Familiar Enemy With A New Twist (it grows wings or shoots lasers or regenerates)
4. Set Piece Fight! (a flowing river, a collapsing canyon, an ancient megastructure)
5. Emergency Deployment (no time for the usual prep work. And also, one of your weapons is missing, your usual crew is unavailable, or your arm still hasn't been reattached)
6. Bulwark vs Bulwark (they corrupted one of your NPC allies, raised one from the dead, or you need to show off your moves to get a hot date).
Giant 4, Chenthooran Nambiarooran

Secret Metaplot and Endgame Ideas

Why are Great Beasts crawling out of the sea, out of caves, out of the sky? These types of stories always have a convoluted metaplot.

1. A secret portal between dimensions or planes. Close it, or cross over and find out who is behind this. Then punch them with your giant mecha.
2. It really is the Apocalypse. The Gods are angry at your defiance. Climb into heaven and kick them to the curb.
3. The Folly of Man. Some ancient wizard, potions of giant growth, forbidden magic, etc, etc. Turns out the people who you report to supported him as well. It's all a cover up! Find out the truth and reveal their treachery to the people.
4. Hell wants to take over the world. It's like the Apocalypse, except the Gods are on your side. Descend into Hell and kick Satan in the goolies.
5. It's all allegorical. The world is already in Hell or something. Maybe this is training for the real war in Heaven? Maybe it's a way of shriving your sins?
6. There a really evil wizard out there. He's just a really bad dude. Nothing complicated, go chop off his head. Oh wait, he's already dead or something, or immortal, or the step needed to kill him are very obscure. There might be a prophecy.

Ideas for Feature Equivalents

Mortal Scale Bulwark Scale
Boarding Actions Disease Rules
Pit Trap Canyon covered in a tarp, sinkhole
Dart Trap Giants with flaming bows and arrows
Poison Gas Trap Underground coal fire, huge urns
Potion of Healing Liquefied mana burst

Great Beasts

Here are 4 particularly horrifying Great Beasts. Each one is an apocalypse.

Promotional Image, the BFG

1. The Wretched

Stats: as Goblins
200' tall, but they do not walk like men. They crawl on long fingers and toes, pressed low to the ground, scuttling around hills. They only attack at night. Pale white fingers with black nails flitting by your window, peeling the roof from your stables to eat your horses. Red staring eyes the size of a hut staring, unblinking, through the rafters. The smell is horrifying, but they use the wind to conceal their approach. If you can smell them, it is too late. Somehow, they move silently.

Their weapons are scavenged from fallen Bulwarks.

They own the hills. Captive villages toil to raise flocks for their consumption. They take hostages, perform feints, set traps. They are cunning, these giants, these wretched things. Cunning but always hungry. If you see one, ten more wait. They are a locust plague.

Helix Spitzer, NASA

2. The Tyrant

Stats: as a Beholder
A fallen moon. A corrupt sun. A 250' diameter sphere of scales that eat light. So dark it makes a mockery of midnight. And then the stars appear: ten stars on ten stalks the size of ancient trees, waving slowly. There is a central eye, but it is closed, for now. It only opens to bring utter and final death to its target: a city, a nation, a group of Bulwarks. A world. There is a mouth full of black teeth, carved with invisible runes, sharpened by invisible spells. You will not see the mouth until it is too late.

Every hour after the Tyrant is sighted on the horizon, one of the effects below occurs, in order. Each hour, a new eye-star ignites. Each time the Tyrant is reduced to 1/2, 1/4, and 1/10 its starting HP, there is a 50% chance it will activate the next ability listed ahead of schedule.

1. Pacify. No humans within 750', unless actively protected by magical shielding (such as a Bulwark) can take any hostile action against the Tyrant. Instead, they feel compelled to worship it in calm, unfocused rites. Many blind themselves, the better to see the transcendant darkness of their new master.
2. Reverence. As Pacify, except the effect now applies to all animals, beasts, and lesser monsters. They bow down before the Tyrant. The range slowly spreads to 2000'.
3. Rest. The light from this eye is dim, but flares like a lighthouse if the Tyrant is threatened. It is a Bulwark-scale sleep spell, with a single target. 1000' range.
4. Control. Bulwark-scale telekinesis. 6.5 tons of matter at once. As the Tyrant moves, it smashes villages, uproots forests, dams rivers, topples windmills. The force-pressure of the effect is always visible as a moving crater, like a pen pressing into a map and leaving a furrow. It orbits the Tyrant in winding patterns, like a child idly dragging a stick through an anthill. 1000' range.
5. Fear. A stabbing flicker of light. On the Bulwark-scale, a normal fear effect. On the mortal scale, anyone weak-willed must hide from the light, or give in to the siren song of the Tyrant and begin to worship it. Riots. Gibbering panic. The reign of Saturn. Range is line of sight - and at a great distance, at night, it might be mistaken for just another star, low to the horizon.
6. Slow. The air thickens in the light of the seventh eye-star. Bulwark-scale creatures are affected as the slow spell, but can Save each round. On the mortal scale, there is no Save. You move underwater, hideously slow, trapped in amber, and prey to the other lights. 2000' range, radiating in all directions.
7. Lesions. A needle of light, thin like a laser, but deadly and precise. Reaches down and pops people one by one, sliding white-glass beads along its string of light and cracking them open. Roves, searching for the most fearful and isolated. Against a Bulwark-scale target, cause serious wounds. 2500' range. The opening salvo.
8.  Death. A brilliant white beam, solid like a bar of iron. A death ray to Bulwark-scale creatures. To anything smaller, it's just death, simple, absolute, and unavoidable. Rivers stop flowing. Fires go out.
9. Petrify. A sweeping spotlight of death. Grass, flesh, wood - all solidfy into spongy grey stone instantly. Ash flakes through the air. Worshipers are petrified where they stand. Bulwark-scale creatures get usual saves against this flesh to stone ray. Mortal-scale creatures are not so lucky. 1500' range.
10. Immolate. A second white spotlight, racing after the first, flickering on and off. Bulwark-scale disintegrate. Village evaporate. Hills are planed flat. The ash cloud becomes a hurricane, whipped by the light of the Tyrant. 1000' range.
11. Apocalypse Ray. The central eye opens wide and floods the world with light. 7000' range. A mile-long beam of pure destruction. Matter, being tied up in magic to some extent, simple ceases to exist. Grey, dull stone might remain, but worked stone, soil, flesh, and air evaporate into nothingness. The Tyrant sweeps the beam from side to side, leveling mountains. Bulwarks and other immensely magical creatures treat this as an anti-magic ray, but also require a secondary save not to die.
Soul of Innistrad, MTG

3. Corpseworm

Stats: as a zombie
200' long but 200' high, a bent, hunched figure. A mass grave, raised from the dead, fused into one will and one purpose. A tangle of shipwrecks. A mortuary-construct with temple eyes. It lurches, slowly, dropping smaller corpses. The entire thing is a dungeon, and it has a heart you can kill.

Threshold of the Gods, Sam White

4. Raised Angel

Stats: as a Wight
A dark mirror of a bulwark. Celestial armor, pitted with metorite strikes. A flaming sword that went out eons ago, now just drips with the raw absence of fire. Immortal flesh, raised from the dead, sent to blight the living. Its touch poisons farmland, freezes rivers, cracks trees. The winds flee before it, carrying storms. Apocalypse cults worship it as their deliverance, or spring up in its wake.


  1. Bloody marvellously evocative. Round of applause.

  2. This is one of the most awesome ideas I've seen in a very long time. I will definitely write some related campaign material for my players to ignore!