The projectile is not accelerated by the shot. The projectile lives accelerated.

A 100 kg tungsten rod at 0.01c (3,000 km/s) carries ~107 kilotons of kinetic energy. No warhead. No radiation. At this velocity, the explosive is velocity.

You don't build a gun. You build a storage ring: a necklace of superconducting deflector stations in low orbit, where pre-accelerated rods circulate for weeks, waiting. Holding them costs almost nothing — magnetic bending does no work. Firing does: one station dumps its capacitor reserve into a single hard inward kick, bending a rod off its safe chord and down into the atmosphere. A rod left alone just stays in orbit forever — to hit dirt, a station has to shove it down.

How it works

Research Kinetic Bombardment, then deliver Deflector Stations to the hub of a platform orbiting your target planet — the ring assembles itself, one station per second. Load tungsten rods into the same hub and the ring pulls them in and spins them up to cruising speed in the background. When the ring is hot, point the Mass Driver Targeter at the ground and wait three seconds for impact.

Tungsten rods are crafted from tungsten plates, carbon, copper cable, and rocket fuel — the rod's own engine charge: it accelerates itself to 0.01c, while the ring merely holds it. Deflector stations are built from LDS, accumulators, processing units, and copper cable.

Damage

Every strike is Relativistic: damage is subtracted straight from health (a lethal hit deletes the target), so no percentage resist, flat resist, per-hit damage cap or "overkill protection" can stop it — exactly the armour packs like Rampant fixed bolt onto every damage type. The same impact also lands impact, physical and explosion damage through the normal system, so vanilla armour and other mods still react.

It rolls out as an expanding shockwave: the core takes the penetrator hit at the moment of impact, the front rolls outward to the rim over a few seconds, and every pulse hits whatever is under it — so it grinds down even a fat regenerating biter. Add a fireball with ground fires, or turn it off, in settings.

Clearing a map

• Carpet bombardment — drag the targeter over a nest field and it rains one rod per nest cluster, clustered by blast radius so no rod is wasted (densest clusters first if the ring runs low).
• Auto-fire (orbital patrol) — optional hands-off mode: every interval each ring bombs the nearest enemy nests, and worms, within radar coverage on its own.
• Drop-and-go logistics — a freighter dumps its whole load of rods into the ring's buffer and leaves; the ring spins them up one at a time, no need to stay parked.

Physics & features

• Half-built rings already work: held speed scales with station count, damage as N squared, blast radius as the cube root — a weak ring hits softer but charges faster.
• Holding charged rods is nearly free — but every bend kicks back, so the ring really station-keeps on the recoil of the rods it throws. Starve it of power and it falls out of the sky.
• No cooldown between shots by default: rate of fire is limited only by how many rods are charged and how fast the ring spins up new ones.
• Per-planet, per-force rings, with a live status window: stations, power, charged rods and spin-up countdown, plus pause/resume.
• A visible incoming tracer, an expanding shockwave, scorchmarks and smouldering smoke — all toggleable cosmetics.

Settings

Adjustable at runtime: center damage, fire damage, blast radius, damage pulses and their timing, rod spin-up time, ring capacity, stations for a full ring, friendly fire, destroying trees, and
the auto-fire mode (interval, radar range, whether to also hit worms).

This mod started as a petty revenge fantasy against a Rampant nest that burned down my factory. Nauvis isn't Earth — but the biters don't get to know that.

Roadmap

Ideas in the works — partly thanks to the orbital-mechanics homework people have been doing in the comments:

• Defensive fire: rings that also bomb the swarm running at your radars and outposts, not just the nests — so you can actually hold reclaimed ground.
• Carpet and patrol that also catch worms and loose biter clusters, not only spawners.
• Tiers of bombardment: a crude, inaccurate "rods from god" gravity drop early, with the full storage ring as the endgame upgrade.
• Infinite accuracy research: early shots scatter by ~100 tiles, late shots land surgical.
• A real orbital power economy: separate ring-keeping vs impact-deflection hardware, capacitor banks, higher-tier power (fusion, Aquilo), and a firing cooldown that comes from the recoil kick.

Suggestions welcome. This thing is being reverse-engineered better in the comments than I engineered it.