Noise and Aliens

The creatures Decided

Big, beastly, powerful creatures that are blind (or nearly) and sense the world through sound and vibration (A Quiet Place vibe).
Evolite is part of their biology. Their “technology” is evolution. They have never used Evolite the way humans do.
They aren’t destructive for its own sake. Noise makes them angry. When the noise stops they have other priorities (mostly reproduction back at the hive), so they turn and go home.
They aren’t punitive or strategic. They go in, make the noise stop, and leave.
A quiet base is safe even with a visible hive about 50 tiles (200 m) away.
The aliens are hostile but primarily defensive.

Noise Decided

Almost everything that operates makes noise: miners, drills, trucks, Harvesters (a little), factories.
Passive structures (walls, silos, idle buildings, barracks) make little or none. Whether idle (blocked or starved) machines make noise is Open.
Noise is additive. Each source makes a constant amount. Neighboring sources combine so the circle grows somewhat larger than the overlap alone. This “combination effect” is slightly additive, not massively.
Noise is shown as a toggleable map overlay: a circle or area of influence around your activity. Fog inside the noise zone is drawn hatched (see world.md).
Turrets and military units count as “noise” for targeting. They have an artificial threat value, because creatures recognize what hurts them and go for it first.
Harvester swarms are quieter than drills, even when saturating a deposit. That makes them a legitimate run-quiet strategy (see resources-and-economy.md).

Should ordinary mines also ramp up? Open

One idea: a whole network of mines keeps growing its circle over time, like the big drill but milder, slowly drawing in new enemies at remote sites. That gives a reason to switch mines on and off, or put them on timers. The worry is that forcing everyone to manage it gets tedious. Unresolved.

Seismic signature: the big drill Decided

The Evolite Drill produces a seismic signature, a separate concept from noise.
It ramps up while running. The circle keeps growing as long as the drill is on.
It spools down slowly when turned off. You can’t grow the circle to the size you want and snap it off. The aggro you’ve caused stays for a while.
Creatures far out may lose the sound as it shrinks away and turn back. Close or fast ones keep coming. Creatures move at different speeds.
Seismic disturbance angers creatures day or night.
If you’re greedy enough, the circle can cover nearly the whole map, and possibly wake a boss in the fog.

Alien behavior model Decided

1. Attraction (long range)

Creatures that hear noise head toward the sound without picking a target. If the noise stops or shrinks away before they arrive, they get confused and turn around.

2. Target acquisition (close range)

Up close they lock onto targets in priority order:

Aggressive structures: turrets and military units.
Noise-making structures, by distance, not volume. The nearest thing making noise.

The loud drill deep in your base is what pulls the swarm in, but the creatures chew through every noisy factory on the way. The drill may never be what gets destroyed.

3. Commitment and memory (“momentum”)

Once locked on, a creature tries to destroy its target.
If it was just shot by a turret, it remembers the pain and destroys that turret.
If it is next to a structure that was making noise, shutting that structure off doesn’t save it. It still gets destroyed. The creature won’t necessarily move on to the quiet building next door.
If its target is deep inside the base and the noise stops while it’s still at the walls, it backs off sooner.
Momentum prevents toggle-kiting (rapidly flipping power to manipulate aggro). Expect a cooldown or tail before creatures disengage.

4. Swarming and spread

Some randomness keeps them from clumping.
If a creature sees two or three others already attacking a structure and has another target available, it picks the other one.
The goal is a swarm tearing through the base, not a single pile-on.

5. Collateral

Anything in the way gets destroyed: walls, silos, foundations. Creatures will run past a silo to reach noise, but destroy it if it’s in their path.

6. Pathfinding Decided

Basic creatures pathfind around walls for short detours (about 20 tiles, 80 m). Anything longer, they break straight through.
Other creature types and bosses may behave differently.
This makes wall thickness, chokepoints and defended gaps matter.

7. Retreat

Creatures retreat when the noise stops, when resistance is overwhelming, or when going home looks better than staying.
They return to the hive rather than fighting to the death. Fights end with retreats, not just wipes.

Consequences for the player Decided

Shutting down is a defense. Turning machines off silences them, and eventually the attackers leave.
Losing power can save you. If a generator is destroyed, everything it powered goes quiet (electrified tier). Colite-burning machines have their own fuel and keep running and making noise.
Passive structures survive. After an attack, a large part of the base is usually still standing.
Base layout matters: production on the outer walls is a bad idea, and silos shouldn’t sit in the path to noise sources. Players learn this through failure, and that’s intended.
Electrification has a defensive benefit, not just an efficiency one: you can silence a whole district by cutting its power.

Hives

Live Evolite Decided

A hive is Live Evolite: Evolite that spawns creatures.
Hives spawn weak creatures that mate to produce larger ones Tentative. An untouched hive grows more dangerous over time without arbitrary level scaling.
Hives sit on Evolite.
Clearing a hive is a combined operation: kill the defenders, keep enough military there to hold it, then send Harvesters to collect the Live Evolite (“popping the eggs,” bursting the nest). Harvesting is quick and easy; the fighting is the hard part.
Harvesting a hive does not provoke extra defenders Decided.
One Harvester with one stack of cargo needs many trips. A fleet clears it fast. Forward depots make this practical.
Once all Live Evolite is removed, the hive stops spawning.
How dangerous a hive is should be readable on sight, either from its size or a label, so players can tell “we can’t possibly attack that” Tentative.

Expansion and recolonization [Decided in principle]

Like other factory games, aliens can found new hives and creep closer if left unchecked.
Clearing an area is temporary. The only way to keep it safe is to hold it: outposts, outer walls, radar, and destroying returning hives.
Mechanism under discussion: uncollected dropped Evolite turns into a dormant seed, then a new hive, possibly needing a critical mass nearby [Open — deferred]. For the prototype, dropped Evolite simply disappears after about 5 minutes Decided.

Bosses [Decided in concept]

Huge creatures hidden in the fog, which the player may not know exist.
Long drilling can pull one in. A boss fight is a consequence of the player’s choices, not a scripted event.
Bosses can break the basic behavior rules (different pathing, wall-breaking, and so on).
Their existence makes exploration worthwhile: knowing what’s out there tells you how hard you can drill.
Do bosses roam or stay dormant until disturbed? Open
Names and classes: Open