> ## Documentation Index
> Fetch the complete documentation index at: https://docs.eucaengine.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Capabilities

> Everything the engine exposes, each linked to its page — the build / simulate / render / experiment surface, in full.

Euca is one [typed HTTP API](/api-reference/introduction) over a deep engine. Every capability below
links to its own page, and every endpoint is in the
[API reference](/api-reference/introduction).

<Note>
  **Hosting — three classes.** Most of the engine runs **headless**: world, simulation, physics,
  gameplay, navigation, the *logic* of animation/particles/terrain/UI, and input. What needs more:
  **(1)** visible output (rendering, camera) needs a GPU/render host; **(2)** audio and Lua scripting
  need their own resource — an audio device, a script VM — not a GPU; **(3)** a few subsystems
  (templates/prefabs, input bindings, scripting) need their resource registered, which a bare
  headless host doesn't do unless the project's game does. Each page says which applies; see
  [Troubleshooting](/reference/troubleshooting).
</Note>

<Note>
  **"AI" here is never an in-engine LLM.** The *agents* that drive Euca are external clients; in-engine
  AI is classical and deterministic ([behavior trees](/systems/ai-behaviors)), and
  [asset generation](/systems/asset-generation) calls external 3D-gen providers and never touches ground
  truth.
</Note>

## Build a world

<CardGroup cols={2}>
  <Card title="Entities & components" icon="table-cells" href="/concepts/world-as-table">
    Spawn/despawn, patch components, tag, observe — the world as a table.
  </Card>

  <Card title="Rules as data" icon="diagram-project" href="/concepts/rules-as-data">
    `when X do Y` as inspectable data, changeable mid-run.
  </Card>

  <Card title="Templates & prefabs" icon="copy" href="/systems/templates-and-prefabs">
    Reusable runtime templates and static registered prefabs.
  </Card>

  <Card title="Scenes & levels" icon="map" href="/systems/scenes-and-levels">
    Load a whole world from one scenario; save/load scenes and levels.
  </Card>
</CardGroup>

## Simulate & play

<CardGroup cols={2}>
  <Card title="Simulation" icon="play" href="/systems/simulation">
    The deterministic tick loop, play/pause/step, match lifecycle.
  </Card>

  <Card title="Gameplay & combat" icon="burst" href="/systems/gameplay-and-combat">
    Health, damage/heal, projectiles, triggers, teams, scoring.
  </Card>

  <Card title="Abilities & status effects" icon="wand-magic-sparkles" href="/systems/abilities-and-status-effects">
    Cooldown/mana abilities, stat modifiers, DoTs, crowd control.
  </Card>

  <Card title="Units & roles" icon="user-shield" href="/systems/heroes">
    Compose units from gameplay components — health, team, combat, gold, roles.
  </Card>

  <Card title="Inventory & economy" icon="coins" href="/systems/inventory-and-economy">
    Inventories, equipment, and the gold economy.
  </Card>

  <Card title="AI behaviors" icon="robot" href="/systems/ai-behaviors">
    NPC steering + a behavior-tree library. Classical, not an LLM.
  </Card>

  <Card title="Navigation" icon="route" href="/systems/navigation">
    Grid navmesh, A\* pathfinding, steering agents.
  </Card>

  <Card title="Input" icon="keyboard" href="/systems/input">
    Key/mouse/gamepad bindings, action maps, a context stack.
  </Card>
</CardGroup>

## Render & present

<CardGroup cols={2}>
  <Card title="Camera & rendering" icon="video" href="/systems/camera-and-rendering">
    Camera control + the PBR forward renderer. Needs a GPU host.
  </Card>

  <Card title="Materials & post-processing" icon="palette" href="/systems/materials-and-post-processing">
    PBR materials, the post stack with presets, volumetric fog.
  </Card>

  <Card title="Animation" icon="film" href="/systems/animation">
    State machines, blend spaces, montages, root motion, IK.
  </Card>

  <Card title="Particles" icon="sparkles" href="/systems/particles">
    CPU emitters — gravity, aging, color-over-life, shapes.
  </Card>

  <Card title="Terrain & foliage" icon="mountain-sun" href="/systems/terrain-and-foliage">
    Heightmap terrain, brush editing, colliders, instanced foliage.
  </Card>

  <Card title="UI & HUD" icon="window-maximize" href="/systems/ui-and-hud">
    Flex layout, widgets, hit-testing — HUD text and bars.
  </Card>

  <Card title="Audio" icon="volume-high" href="/systems/audio">
    Spatial + global audio, buses, reverb, occlusion. Needs a device.
  </Card>

  <Card title="Asset generation" icon="cube" href="/systems/asset-generation">
    Text/image → 3D across 4 wired providers (Tripo, Meshy, Rodin, Hunyuan); appearance ≠ ground truth.
  </Card>
</CardGroup>

## Experiment & verify

<CardGroup cols={2}>
  <Card title="Forks & counterfactuals" icon="code-branch" href="/concepts/forks">
    Deep-clone the world, intervene, diff, drop.
  </Card>

  <Card title="The world-engine API" icon="eye" href="/concepts/query-verbs">
    observe · peek · step · fork — and the `peek == step` invariant.
  </Card>

  <Card title="Assertions & manifest" icon="clipboard-check" href="/systems/assertions-and-manifest">
    Testable expectations, probe, a self-grading feature manifest.
  </Card>

  <Card title="Determinism & replay" icon="rotate-left" href="/concepts/determinism">
    Byte-for-byte reproducible runs; the `state_digest` oracle.
  </Card>

  <Card title="Datasets" icon="database" href="/systems/datasets">
    Exact structured state + ground-truth segmentation/depth channels.
  </Card>

  <Card title="Evaluation" icon="flask" href="/evaluation/overview">
    Grade any world model against exact ground truth, in nats.
  </Card>
</CardGroup>

## Platform & tools

<CardGroup cols={2}>
  <Card title="The euca-studio editor" icon="pen-ruler" href="/concepts/two-faces">
    The visual editor — open any project, edit the scene as data, press Play. The game-engine face.
  </Card>

  <Card title="The euca CLI" icon="terminal" href="/concepts/the-cli">
    A command-line client mapping to the HTTP API, with discover/explain.
  </Card>

  <Card title="Networking" icon="network-wired" href="/concepts/networking">
    A snapshot/delta replication + prediction library (not yet wired).
  </Card>

  <Card title="Scripting (Lua)" icon="scroll" href="/systems/scripting-lua">
    Sandboxed per-entity Lua with an ECS bridge and hot reload.
  </Card>

  <Card title="MOBA systems" icon="chess-rook" href="/systems/moba">
    A full Dota-style kit on the genre-neutral primitives.
  </Card>

  <Card title="Hosting & deployment" icon="server" href="/systems/hosting-deployment">
    Run a server, target it — unauthenticated by default, with opt-in Ed25519 auth.
  </Card>

  <Card title="The full API" icon="list" href="/api-reference/introduction">
    \~114 endpoints, grouped, with schemas and a playground (hand-maintained OpenAPI snapshot).
  </Card>
</CardGroup>