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Bevy Genre Tower Defense
Thin Bevy genre router for Tower defense. Godot counterpart: godot-genre-tower-defense. Keywords: Bevy, Tower defense, genre, ECS, router.
Archived 2026-10-23 · Source updated 2026-10-11 · License: LGPL-3.0. Check the original repository for the latest version.
SKILL.md instructions
# Bevy Tower defense (thin router) Thin genre router. Not a full port. Godot counterpart: godot-genre-tower-defense. Ideas only. Domain work stays on the Bevy skills below. ## When to use Load this for towers, creeps, and waves on a path. ## ECS shape - **Components** hold the genre's per-entity flags as plain data. This file does not name new engine types. - **Resources** hold run-wide counters (score, wave index, seed) via bevy-data-resources. - **Systems** read those components on `Update` or the fixed timestep from bevy-master. Order them with `.chain()` when a later system must see the result. - **Schedule:** gameplay mode changes go through bevy-state-machines. Do not invent a genre plugin. ## Godot idea to Bevy idiom | Idea | Bevy idiom (idea only) | | --- | --- | | Genre scene tree | Entities plus the domain skills linked below | | Autoload director | A resource, not a singleton node | | Signal bus for the loop | bevy-events-messaging | ## Routing - [bevy-game-loop-waves](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-game-loop-waves/SKILL.md) - Creep waves. - [bevy-navigation](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-navigation/SKILL.md) - Path gap. - [bevy-combat-system](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-combat-system/SKILL.md) - Tower shots. - [bevy-economy-system](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-economy-system/SKILL.md) - Build costs. ## Gaps - No tower or path-follow type exists in Bevy. - The navigation mesh is still a gap. ## Expert Knowledge Delta Library target in prose: **Bevy 0.20.0**. Lattice URLs stay unversioned. Opened canon only: `Component`, `Resource`, `Query`, `Commands`, `Startup`, `Update`, `Fixed` / `FixedMain` (`bevy::time`), `.chain()`, `Plugin`, `DefaultPlugins`, `MinimalPlugins`. Messages and observers are an ownership slot. This file does not invent their struct APIs. Systems run in parallel unless `.chain()` orders the ones that conflict. ### Who owns state | Piece | Owner | Who may mutate | Schedule | | --- | --- | --- | --- | | Data on one entity | `Component` | One system via `Query` | `Update` or `FixedMain` | | One value for the whole app | `Resource` | One system | `Startup` to insert, then the schedule that reads it | | Spawn | `Commands` | The spawning system | `Startup` for the initial world; later schedules for runtime spawn | | Order that must not race | `.chain()` | The chained systems only | Same schedule | | Plugin boundary | `Plugin` | `build` registers systems and resources | Before the app runs | Borrow rule: two systems that both mutably query the same component must be ordered (`.chain()`) or split so only one writes. Unrelated systems stay parallel. That is the ECS page rule, not a guess at a system-set API. ### Decision | If you need | Do this | Do not | | --- | --- | --- | | Per-entity data | `Component` + `Query` | A Godot node script | | App-wide config or clock | `Resource` | Copy the value onto every entity | | Stable simulation step | `FixedMain` and the `Fixed` clock | Tie simulation to raw frame `Update` | | Startup spawn | `Commands` in `Startup` | Spawn from a render system | | Cross-system notice that is not shared state | Message or observer slot in `bevy-events-messaging` | A new event type invented in this file | | An API this skill did not open | A Gaps row | A fabricated crate (solver, navmesh module, net, XR) | Load `references/a-gate-notes.md` for the same table plus the gap rule. ## NEVER - Do not put `/0.20.0/` in lattice URLs. WHY: permalinks stay on `latest`. The 0.20.0 pin belongs in prose once. - Do not mutably query the same component from two unordered systems. WHY: the schedule runs systems in parallel unless `.chain()` orders them. - Do not invent a physics, navigation, networking, or XR crate here. WHY: those rows are gaps, blocked, or revisit. - No Godot types in Bevy code. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No invented genre APIs. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No Creation Station content. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - No umbrella skill over Godot and Bevy. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - Do not mark this row `ported`. It is `docs_mapped`. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. - Do not pick a physics or net crate here. WHY: a Godot port, an unopened API, or a public lie fails the docs-first bar. ## Reference docs.rs links use the unversioned `latest` permalink. The library pin on bevy-master stays **0.20.0**. ### Official Documentation - [Migration guides](https://bevy.org/learn/migration-guides/introduction/) - Unversioned hop index. - [bevy crate](https://docs.rs/bevy/latest/bevy/) - Unversioned API index. Feature list opened for 0.20.0. - [Assets](https://bevy.org/assets/) - Official asset catalog. No third-party crate was selected. - [Examples](https://github.com/bevyengine/bevy/tree/latest/examples#examples) - Example tree on the `latest` branch. - [ECS](https://bevy.org/learn/quick-start/getting-started/ecs/) - `Component`, systems, `Query`, `Startup`, `Update`, and `.chain()`. - [Plugins](https://bevy.org/learn/quick-start/getting-started/plugins/) - `Plugin`, `DefaultPlugins`, `MinimalPlugins`, and `add_plugins`. ### Related Skills #### Prerequisites - [bevy-master](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-master/SKILL.md) - ECS ownership and schedules. - [bevy-ecs-composition](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-ecs-composition/SKILL.md) - Spawn and query shape. #### Complements - [godot-genre-tower-defense](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/godot-genre-tower-defense/SKILL.md) - Godot counterpart. Source idea only. - [bevy-game-loop-waves](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-game-loop-waves/SKILL.md) - Creep waves. - [bevy-navigation](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-navigation/SKILL.md) - Path gap. - [bevy-combat-system](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-combat-system/SKILL.md) - Tower shots. - [bevy-economy-system](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-economy-system/SKILL.md) - Build costs. #### Downstream / consumers - None. This router does not own a second implementation. #### Master - [bevy-master](https://github.com/thedivergentai/gd-agentic-skills/blob/main/skills/bevy-master/SKILL.md) - Bevy router.