Static Top Down Shooter

A 2D top-down shooter built in Unity 6 on the StaticEcs framework. The player runs around a map shooting at enemies that use Utility AI to find cover and return fire. Everything ticks inside one ECS world across three system groups: input, update, physics.

Key dependencies

• StaticEcs for ECS
• NavMeshPlus for NavMesh
• Wise Feline (Lite) for Utility AI

Controls

Action	Binding
Move	WASD or arrows
Aim	Mouse
Shoot	Left mouse
Dash	Space

Bindings live in Settings/InputMap/PlayerInputActions.inputactions.

Project layout

src/StaticTopDownShooter/             Unity project (6000.3.10f1)
└── Assets/
    ├── _Project/
    │   ├── Code/
    │   │   ├── Common/Extensions/    Transform, Vector, Enumerable, Numeric helpers
    │   │   ├── Editor/               Editor-only assembly
    │   │   └── Gameplay/
    │   │       ├── Core/             ECS bootstrap, world type, providers, registrars
    │   │       ├── Common/           Collision broadcasters, time, transform refs
    │   │       ├── Input/            PlayerInputActions wrapper + emit systems
    │   │       └── Features/
    │   │           ├── Aim/          Cursor-driven reticle
    │   │           ├── Ai/           Edited Wise Feline utility-AI core + editor
    │   │           ├── Animation/    Sprite and Animator wiring
    │   │           ├── Cameras/      Camera follow
    │   │           ├── Enemy/        Tags, AI considerations and actions, cover system
    │   │           ├── Lifetime/     HP, damage, death events
    │   │           ├── Movement/     Rigidbody2D move and dash
    │   │           ├── Player/       Player tag
    │   │           └── Weapon/       Bullet spawn, fire-rate gate, recoil, hit damage
    │   ├── Art/                      Project-authored animations + tilemap palette
    │   ├── Resources/Gameplay/       Runtime-loaded prefabs (Bullet, Rock, settings)
    │   ├── Scenes/Battle.unity       Gameplay scene with baked 2D NavMesh
    │   └── Settings/                 InputMap, URP, Editor configs
    └── ThirdParty/Tiny Swords/       Pixel art pack

Architecture

EcsRunner is the only bootstrap MonoBehaviour. On Start it creates one Game world, registers every IComponent / ITag / IEvent / IResource it can find in the Shooter assembly, then builds three system groups:

Group	Tick	Runs
InputSys	Update (early)	Reads Unity input, emits move and aim events. Also where enemy AI rethinks and steers.
UpdateSys	Update	Aim, shoot cooldown, bullet spawn, dash, damage, animation, camera follow, view cleanup.
PhysicsSys	FixedUpdate	Rigidbody2D movement, impulse application, bullet rotation toward velocity.

Scene entities are created by AbstractStaticEcsEntityProvider components. Any MonoBehaviour implementing IResourcesRegistrar can register a shared resource (main camera, follow settings) at boot. Per-entity setup uses two MonoBehaviour layers: each scene entity has a RootGameComponentsRegistrar that holds a list of GameEntityComponentsRegistrar subclasses (EnemyTagRegistrar, BrainComponentRegistrar, EntityColliderRegistrar, and so on). At boot the root walks the list, and each subclass adds its tags or components to the entity.

Two StaticEcs entity-type markers (IEntityType) are declared: CharacterET for the player and enemies, BulletET for projectiles. They are framework identifiers, not Unity types, that StaticEcs uses to group entities of the same kind.

Enemy AI

Enemies don't have their own movement code. The AI writes to the same MoveInput component (and aim pipeline) the player input fills, so movement, animation, and weapon systems treat them identically. It just decides what those inputs should be each frame.

A Utility AI sits behind each enemy. Every RethinkInterval seconds the Brain scores its available Actions against the current game state and switches to the highest scorer.

Actions:

• Idle: stand still while an internal timer runs down.
• Patrol: walk between waypoints in order.
• MoveToCover: pick the nearest cover point and navigate to it.
• AttackFromCover: face the player and fire from the current cover slot.

Pathfinding uses 2D NavMesh+ agents. The agent's desiredVelocity is written into MoveInput each frame, so the rest of the pipeline behaves the same as for the player.

Collisions

CollisionEventBroadcaster is attached only to objects whose 2D collisions need to reach ECS (right now just the bullet prefab) and pushes their collision and trigger events into GameEventProvider. ColliderRegistry lets a system resolve a Collider2D back to its owning entity.

The damage chain runs through this same hub. When a bullet's trigger fires, HandleBulletCollisionInputSystem resolves the other collider to its entity and sends a DamageEvent for the target plus a DeadEvent for the bullet itself. ApplyDamageSystem then subtracts from Hp and emits a DeadEvent when health hits zero. DestroyViewByDeadEventSystem tears down the view GameObject for any entity it sees in a DeadEvent.

Build and run

1. Install Unity 6000.3.10f1.
2. Open src/StaticTopDownShooter/ in Unity Hub. The first import resolves the Git-based packages.
3. Open Assets/_Project/Scenes/Battle.unity and press Play.

Resources

Art

All third-party visuals sit in Assets/ThirdParty/Tiny Swords/.

• Tiny Swords pixel art pack by Pixel Frog: https://pixelfrog-assets.itch.io/tiny-swords