Auto Warz — Vertical Layers & Core Power System

Document Type: Design Document Version: 0.1 Last Updated: 2026-02-26 Vault destination: 01_Design Documents Related Documents: [01_Master GDD](<./01_Master GDD.md>) · [04_Factory & Resource System Design](<./04_Factory & Resource System Design.md>) · [05_World Generation & Planet Types](<./05_World Generation & Planet Types.md>) · [[08_Economy & Progression Design]] Folder: 01_Design Documents

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Overview

Every planet in Auto Warz has a vertical dimension — players can build factories underground into the planet's crust and upward into the sky. Each level is a separate grid connected to adjacent levels by Item Lifts, Fluid Risers and Power Conduits (underground) or open-air connections (sky). This allows players to design factories vertically as well as horizontally, creating multi-storey industrial complexes.

At the heart of the underground system is Core Power — energy tapped from the planet's molten core via a Core Power Station on the surface. Deeper excavation unlocks more of the planet's core energy, supplementing surface generators and providing a powerful long-term energy source unique to each planet.

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Level Structure

Overview

Sky Level 3  ← Solar Panel, Wind Turbine, Atmospheric Harvester (best efficiency)
Sky Level 2  ← Solar Panel, Wind Turbine, Atmospheric Harvester (good efficiency)
Sky Level 1  ← Solar Panel, Wind Turbine, Atmospheric Harvester (reduced efficiency)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
SURFACE      ← All standard buildings + Solar/Wind/Atmospheric (base efficiency)
             ← Core Power Station (built here, taps core automatically)
             ← Geothermal Tap (surface placement — lowest output)
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Underground L1  ← Core Drill, Deep Scanner, Geothermal Tap (20% core energy)
Underground L2  ← Geothermal Tap, all underground buildings (35% cumulative)
Underground L3  ← Geothermal Tap, all underground buildings (55% cumulative)
Underground L4  ← Geothermal Tap, all underground buildings (80% cumulative — max)

Per-Planet Level Counts

Each planet type determines how many underground and sky levels are available. Levels must be unlocked via research before they can be built on.

Planet Type	Underground Levels	Sky Levels
Terrestrial	2	3
Super-Earth	4	4
Ocean	2	3
Lava	3	3
Carbon	3	4
Rogue	2	3
Chthonian	4	6
Mini-Neptune	3	5
Hot Jupiter	2	6

Design note: Underground minimum is 2, maximum is 4. Sky minimum is 3, maximum is 6. Chthonian and Hot Jupiter offer the most vertical space — these are the most extreme and rewarding planets to fully develop.

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Grid Model

• Each level is a separate top-down grid — same grid dimensions as the surface
• Camera stays top-down per level — the player sees one level at a time
• Levels are navigated via the Level Selector (UI panel) or by teleporting Genesis to a level
• Buildings on different levels cannot interact directly — all cross-level material and fluid transfer uses Item Lifts and Fluid Risers (underground) or open connections (sky)
• Power is distributed between levels via Power Conduits (see Core Power section)

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Vertical Transport Structure Model

One Shaft Per Type

Items, fluids, and power each get their own dedicated vertical structure. They do not share a shaft and do not compete for its capacity.

Structure	Carries	Underground	Sky equivalent
Item Lift	Items	Yes	Sky Lift (open air, no structure needed)
Fluid Riser	Fluids and gases	Yes	Sky Pipeline
Power Conduit	Power	Yes	Power Pylon (open air)

The player does not juggle one crowded shaft. They find room for three separate vertical alignments, each occupying matching cells on both adjacent levels. This is a clearer spatial puzzle than contention, easier to balance, and easier to read in the world.

The structural-reinforcement fiction still holds: each of the three provides its own reinforcement.

Each structure uses the standard donut base and port system. They are paired structures, existing on both levels at the same grid cell, as the current shaft rules already require.

• Item Lift — item ports on both levels. Input on one side, output on the other.
• Fluid Riser — fluid ports on both levels.
• Power Conduit — all ports DISABLED — flush cover plates, same as transformers.

Throughput scales with Mk:

• Base Mk raises port throughput, so a higher-Mk Item Lift or Fluid Riser moves more per tick
• Machine Mk raises the Power Conduit's power capacity

No new upgrade mechanism is needed, and it resolves the open question of whether conduit capacity is fixed or upgradeable: upgradeable via Machine Mk.

Cross-Level Power — Capacity Cap, No Loss

Power crossing levels is limited by conduit capacity, not by distance loss.

A Power Conduit is a short, purpose-built, heavy conductor spanning one level boundary. Real risers of that kind are rated by capacity, not by loss over distance — the run is too short for loss to matter.

This is mechanically correct for the game: the player builds a building to move power between levels, so the building is the transfer, and its rating is the governing constraint.

This does not contradict the horizontal model, where voltage drop scales with load over distance. Different geometry and different physical assumptions apply.

A Power Conduit is a rated link between two grids, not a merge. This matters:

• Each level keeps its own grid identity, so the HUD's per-grid breakdown remains meaningful.
• A conduit at capacity means the level below can be in deficit while the surface has surplus, which is a real and readable problem.
• Grid merge and split notifications behave sensibly across levels.

Transmission does not go vertical. High-voltage transmission is horizontal only. Conduits and pylons are the sole vertical paths for power, at distribution voltage.

There is therefore no need for underground transformers and no vertical loss model to build.

Resolution: the clearance rule applies to horizontal transmission lines only. Power pylons run vertically from the surface to the sky and are unaffected.

Genesis & Level Navigation

Genesis is an advanced flying bot — it does not walk on terrain. It hovers and teleports between levels instantly.

• Level Selector UI — player selects any unlocked level from a panel; camera and active grid switch to that level
• Genesis Teleport — Genesis can be directed to any unlocked level; it teleports there instantly with no travel time
• Genesis operates identically on all levels — same task queue, same capabilities
• Underground levels are pre-excavated when unlocked — Genesis does not dig; the level grid becomes available to build on immediately
• Exception: vertical structure cells must be explicitly built by Genesis to connect underground levels (see Vertical Structures)

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Core Power System

Concept

Every planet has a Core Energy Rating — a value representing the total energy available from its molten core. This rating varies by planet type and is generated from the session seed (deterministic per planet).

A Core Power Station built on the surface taps into this energy. The station itself sits on the surface grid but draws power through the planet's geology. Deeper underground levels must be unlocked and excavated to access progressively more of the core energy.

Core Power Station

• Placement: Surface grid only — one per planet (hard limit)
• Unlocks: Available from early-mid research
• Function: Once built, automatically begins drawing from Core Level 1 (shallowest underground)
• Limit: Only ONE Core Power Station per planet at any time
• Output: Starts at Core Level 1 output; increases as deeper underground levels are unlocked

Core Energy Output Formula

Output is based on the planet's Core Energy Rating and how many underground levels have been unlocked. Each deeper level unlocks access to more of the total core energy — it does not multiply, it reveals.

Core Energy Rating (CER) — unique per planet, generated from seed
Defined as: total power units available from the core

Output per level unlock:
Level 1 unlocked: CER × 0.20  (20% of total)
Level 2 unlocked: CER × 0.35  (35% of total — cumulative)
Level 3 unlocked: CER × 0.55  (55% of total — cumulative)
Level 4 unlocked: CER × 0.80  (80% of total — cumulative, max)

Note: 100% is never reachable — the core always retains 20% 
as a design constraint (the planet remains geologically stable)

Example — Terrestrial Planet (CER: 500 PU): - After unlocking Level 1: 100 PU output - After unlocking Level 2: 175 PU output - (Max 2 underground levels on Terrestrial)

Example — Chthonian Planet (CER: 2400 PU): - After unlocking Level 1: 480 PU output - After unlocking Level 2: 840 PU output - After unlocking Level 3: 1320 PU output - After unlocking Level 4: 1920 PU output

Core Energy Rating by Planet Type

Planet Type	Core Energy Rating Range	Notes
Terrestrial	400 – 600 PU	Reliable starter energy
Super-Earth	800 – 1200 PU	Large mass = hot core
Ocean	200 – 400 PU	Cooler, geologically stable
Lava	1200 – 1800 PU	Hyperactive geology
Carbon	600 – 900 PU	Dense but stable
Rogue	100 – 250 PU	Cold, ancient core — low energy
Chthonian	1800 – 2800 PU	Exposed core — highest energy
Mini-Neptune	500 – 800 PU	Compressed core
Hot Jupiter	1000 – 1600 PU	Tidal heating from star

Core Energy Rating is seeded per planet — two Terrestrial planets in the same session will have different ratings within the range.

Power Distribution Between Levels

Core power (and all power) is distributed between levels via Power Conduits — a buildable structure placed in the matching vertical cell between adjacent levels.

• Power Conduits carry power between adjacent levels at a rated capacity
• Surface generators can power underground levels via conduits (and vice versa)
• Sky levels receive power from the surface via open-air Power Pylons (no shaft required)
• Each conduit has a maximum power throughput — upgradeable via Machine Mk
• Conduits do not merge the two grids; they create a bounded link between them

This preserves the distinction between grid-level health and level-to-level transfer. A path can be saturated while the source level remains healthy, making vertical power planning a real strategic constraint instead of a hidden merge behaviour.

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Underground Levels

Unlocking Underground Levels

Each underground level requires: 1. Research unlock — specific research node in the progression tree 2. Vertical structure construction — Genesis builds an Item Lift, Fluid Riser or Power Conduit connecting the new level to the level above

Research nodes per level:

Level	Research Required	Notes
Underground L1	Basic Excavation	Available early-mid game
Underground L2	Deep Excavation	Mid game
Underground L3	Advanced Boring	Late game — not available on all planets
Underground L4	Core Excavation	Late game — only on planets with 4 underground levels

Vertical Structures (Underground Only)

There is no generic Shaft building. Items, fluids and power each get their own single-cell structure, built by Genesis in the underground grid. Each provides its own structural reinforcement, so the soil does not collapse around it.

• The three structures: Item Lift, Fluid Riser, Power Conduit. See Vertical Transport Structure Model above for ports and throughput.
• Placement: each must occupy the same grid cell on both adjacent levels to form a connection. Three separate vertical alignments to find room for, rather than one crowded shaft to fight over.
• Genesis task: PLACE_SHAFT is removed, replaced by the type-specific build task for each structure.
• Research gates: Vertical Lift and Pipe Pump gate the Item Lift and Fluid Riser; the Power Conduit is unlocked separately.

The container-plus-contents model is gone: the structure and what it carries are now the same object, which removes an abstraction layer and makes each vertical route readable at a glance.

Underground-Only Buildings

These buildings can only be placed on underground level grids:

Building	Function	Unlock
Core Drill	Extracts rare deep minerals only found underground	Basic Excavation
Deep Scanner	Scans for rare ore deposits on the current underground level	Basic Excavation
Reinforced Storage	Higher capacity storage — structural underground environment enables larger tanks	Basic Excavation
(more to be added)

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Geothermal Tap

The Geothermal Tap is a power generator that harnesses heat from the planet's geology. It is cheaper and has a smaller footprint than the Core Power Station, making it a practical early-mid game power supplement. Multiple Geothermal Taps can be placed on a planet (unlike the Core Power Station which is limited to one).

Placement

• Surface: Allowed — lowest output
• Underground levels: Allowed — output increases with depth
• Sky levels: Not allowed — too far from geothermal heat source

Output Scaling

Uses the same depth-based formula as Core Power — each deeper level unlocks access to more of the planet's geothermal energy. The Geothermal Tap draws from a Geothermal Energy Pool separate from the Core Energy Rating.

Geothermal Energy Pool (GEP) — unique per planet, generated from seed
Smaller than CER — Geothermal Taps are supplementary, not primary

Output per placement level:
Surface:     GEP × 0.15  (15% of pool per tap)
UG Level 1:  GEP × 0.25
UG Level 2:  GEP × 0.38
UG Level 3:  GEP × 0.52
UG Level 4:  GEP × 0.65  (max — only on planets with 4 underground levels)

Each tap draws independently — placing multiple taps on the same level
each draw their own share of the pool.

Example — Lava Planet (GEP: 400 PU): - Surface tap: 60 PU - UG Level 1 tap: 100 PU - UG Level 2 tap: 152 PU - UG Level 3 tap: 208 PU

Comparison to Core Power Station

	Core Power Station	Geothermal Tap
Limit per planet	1	Unlimited
Footprint	Large	Small
Cost	High	Low
Energy source	Core Energy Rating	Geothermal Energy Pool
Placement	Surface only	Surface + underground
Output	High	Moderate
Best use	Primary power backbone	Supplementary / distributed power

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Sky Levels

Unlocking Sky Levels

Sky levels do not require underground vertical structures — they are open-air platforms built upward. Each level requires research and a Sky Platform structure that Genesis constructs.

Level	Research Required
Sky L1	Basic Construction
Sky L2	Elevated Construction
Sky L3	High Altitude Construction
Sky L4–L6	Advanced Atmospheric Construction (where available)

Cross-Level Transport (Sky)

• Vertical Belts (Sky): Open-air lift belt connecting adjacent sky levels and surface — no shaft required
• Vertical Pipes (Sky): Open-air pipe run — no pump required (gravity assists downward, pump required upward)
• Both available after research unlock

Buildings Placeable on Sky Levels AND Surface

These buildings are not restricted to sky levels — they can be placed on the surface too. Efficiency varies by building type and the level they're placed on.

Building	Surface Efficiency	Sky L1	Sky L2	Sky L3+	Unlock
Solar Panel	60%	80%	100%	120%	Basic Construction
Wind Turbine	70%	90%	110%	130%	Basic Construction
Atmospheric Harvester	50%	75%	100%	125%	High Altitude Construction
Sky Radar	70%	100%	130%	160%	Elevated Construction
(more to be added)

Design rationale: - Surface placement is always valid and useful — players don't need to unlock sky levels to use these buildings - Sky levels reward the investment of unlocking and building upward with meaningfully better output - Efficiency percentages above are baseline values — planet type modifies them (see below)

Planet-Type Efficiency Modifiers

Building	Best Planet	Worst Planet	Notes
Solar Panel	Hot Jupiter	Rogue Planet	Rogue = 0% (no star); Hot Jupiter day side = 200%
Wind Turbine	Hot Jupiter	Rogue Planet	Rogue = 0% (no atmosphere); Ocean = 80% (calm)
Atmospheric Harvester	Mini-Neptune	Rogue Planet	Rogue = 0% (no atmosphere); Carbon = 60% (thin)

Sky-Only Buildings (Sky levels only — NOT buildable on surface)

Some buildings genuinely require altitude and cannot function at surface level:

Building	Function	Min Level	Unlock
High Altitude Observatory	Long-range scanner — greater range than surface scanners	Sky L2	Elevated Construction
(more to be added)

Note: The original "sky-only" category is now mostly "surface + sky" — only a small subset require true altitude. This gives players more flexibility in early game before sky levels are unlocked.

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Vertical Transport — Research Gates

Cross-level material and fluid transport is unlocked progressively via research. In early game, levels are isolated — players must research vertical transport before they can move resources between them.

Research	Unlocks	Notes
Vertical Lift	Item Lift between underground levels	Items move up and down between underground levels
Sky Lift	Vertical Belt between sky levels and surface	No shaft required
Pipe Pump	Fluid Riser between underground levels	Fluids move upward underground; gravity assists downward without a pump
Sky Pipeline	Vertical pipes between sky levels	Pump required upward, gravity assists downward
Power Conduit	Power distribution between all levels	Core power reaches surface; surface power reaches underground

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Visual Design Notes

• Underground levels have a distinct visual palette — darker, lit by industrial lighting, rock/soil walls visible at grid edges
• Sky levels have an open-air look — visible horizon, atmospheric effects, weather visible
• Level transitions shown in the Level Selector UI as a vertical cross-section diagram of the planet
• Camera switching between levels is instant — no transition animation in prototype, smooth fade in later polish pass
• Item Lift, Fluid Riser and Power Conduit cells read from above as reinforced openings in the floor grid, each visually distinct from the others
• Genesis teleporting between levels plays a short teleport VFX

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Implementation Notes

Phase Scope

• Phase 1 (current): Surface only — vertical system not implemented yet
• Phase 2: Underground L1 unlock, Core Power Station, Item Lift, Power Conduit — this is when the vertical system begins
• Phase 2–3: Progressive unlock of deeper underground levels and sky levels
• Phase 3+: Full vertical transport (lifts, pumped pipes), all level-restricted buildings

Data Structure

# PlanetLevelData.gd
class_name PlanetLevelData
extends Resource

enum LevelType { UNDERGROUND, SURFACE, SKY }

@export var level_type: LevelType
@export var level_index: int        # 0 = surface adjacent, increases away from surface
@export var is_unlocked: bool = false
@export var grid: GridData          # separate grid per level
@export var has_shaft: bool = false # underground levels only

# PlanetData.gd addition
@export var underground_levels: Array[PlanetLevelData]
@export var sky_levels: Array[PlanetLevelData]
@export var core_energy_rating: float   # seeded per planet
@export var core_station_built: bool = false
@export var core_levels_unlocked: int = 0  # 0 = station built but only surface; 1-4 = underground levels

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Open items for this document are tracked in docs/open-items.md, area vertical.

Naming

The building is the Solar Panel. Earlier drafts of this document called it a Solar Collector while 08_Research Tree Design and the shipped data called it a Solar Panel; they were always one building with two names. Solar Panel wins on evidence rather than preference: it appears in 13 vault documents against 6, and data/buildings/solar_panel.tres already ships, so the alternative would have required a data change.

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Revision History

Version	Date	Changes
0.3	2026-08-27	Absorbed Vertical Transport & Cross-Level Power.md, which is now deleted. Generic Shaft removed throughout: the Shafts section becomes Vertical Structures, and PLACE_SHAFT is replaced by type-specific build tasks for the Item Lift, Fluid Riser and Power Conduit. Solar Collector renamed Solar Panel everywhere.
0.1	2026-02-26	Initial document — vertical layer system, core power design, shaft mechanics, level-restricted buildings, research gates, per-planet level counts and core energy ratings
0.2	2026-02-26	Surface buildings clarified — Solar Collector, Wind Turbine, Atmospheric Harvester all buildable on surface and sky levels with variable efficiency per level and planet type. Geothermal Tap moved to its own section — surface + underground only, same depth scaling formula as Core Power, smaller footprint, unlimited per planet. Level structure diagram updated.
0.3	2026-08-25	Merged the Vertical Transport & Cross-Level Power addendum: one shaft per type, conduit capacity model, horizontal-only transmission, and correction of the related open questions.