Colony Buildings: Runtime Upgradable System

A PCG-driven upgrade system in Unreal Engine 5 that turns artist-authored levels into a fully automated building pipeline

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The problem: 240+ manual touchpoints per pass

Colony is a mobile AI-driven simulation game where players evolve their colony over time. The city has 16 core buildings, each with 4 upgrade states (empty plot → level 03), and every state affects art, activities, gameplay hooks, and backend data.

The original approach relied on duplicated sublevels, per-actor configuration, and manually placed blueprints resulting in roughly 240–270 manual touchpoints per pass. With even a 5–10% error rate on hand edits, the system didn't scale for fast iteration, new features, or future maps.

16 Core buildings

×4 Upgrade states

~270 Manual edits / pass

0 After automation

Building Upgrade Progression

System Architecture

Layer 1

BP_LoadUnloadUpgrades

Driving the PCG

A single Blueprint controls which state each building should be in. It reads the Upgrade Levels Config (a struct per building state), selects the correct PCG target slot and PCG Building Data Asset, then finds the relevant PCG Volume, sets graph object parameters, and calls Generate.

Upgrade Levels Config PCG Volume Data Asset Generate()

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Layer 2

PCG Graph

Instancing the art

The PCG graph loads the assigned PCG Data Asset and uses it to instance all meshes for the chosen building state. Each building type (Barracks, Hydro, Med Bay…) flows through the same PCG logic ; only the data asset changes. All visual content lives in data assets + level instances, not scattered across sublevels.

PCG Data Asset Mesh Instancing Level Instances

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Layer 3

PCG Graph

Spawning metadata actors

After the art is placed, the same PCG graph analyzes the building bounds and spawns lightweight metadata actors. It passes data from BP_LoadUnloadUpgrades via graph parameters: the building gameplay tag, upgrade level, and slot identifier. These actors hold all gameplay-relevant information and set up triggers for touch events and backend updates.

LocationTag.Greenhouse Upgrade Level Slot ID Touch Triggers

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Layer 4

PostProceduralGenerationSpawn

Self-initializing actors

After PCG finishes, newly created metadata actors listen to PostProceduralGenerationSpawn and configure themselves: gameplay tags (building type, upgrade tier, status), attributes (name, current status, custom flags), and backend/analytics hooks. No manual tagging or per-actor setup required.

Gameplay Tags Attributes Backend Hooks Analytics Flags

Data-Driven Configuration

⚙ Upgrade Levels Config

All behavior is backed by a config struct on BP_LoadUnloadUpgrades. For each upgrade level, the artist sets the PCG Building Data Asset. Shared fields like the Building Tag are pushed both into the PCG graph (for filtering/spawning) and into the metadata actors (so they know what they represent). Changing how a building behaves is mostly a matter of editing this config, not touching dozens of actors.

PCG Building Data Asset DA_Barracks_L02 Defines what PCG instances for this upgrade level

Building Tag LocationTag.Barracks Pushed to PCG graph + metadata actors

PCG Target Slot Slot_Barracks_Main Which PCG Volume / graph slot to target

Upgrade Level 2 Current state index (0 = empty plot, 3 = max)

Impact

⚠ The Original Approach

✗ Duplicated sublevels per building state
✗ Per-actor configuration of gameplay tags and attributes
✗ Manually placed and wired activity blueprints
✗ Repeated setup with every new feature or iteration
✗ UE batching broken by improper instantiation
✗ ~270 manual touchpoints per pass, 5–10% error rate

✓ After PCG Automation

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Zero manual edits per pass

Upgrades, tags, actors, and level loading fully driven by BP + PCG

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Consistent data across disciplines

Design, tech art, and backend read from the same PCG-spawned metadata

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Fast, low-risk iteration

New features = extend config struct + PCG graph, not re-tag actors

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Artists stay in DCC / level land

Author base level + level instances; system handles everything else

Final Result

Colony map overview showing the complete upgradable city with all 16 buildings managed by the PCG system