Your first playable scene

Build a small 3D movement sandbox: steer an anchored cube with WASD while a second cube falls onto a floor. You will create a project, arrange objects, attach a Lua behavior, play, debug and reopen it. This is a playable scene, not a finished exported game: collision events, scoring UI and distributable export are not available as complete workflows here.

Prerequisites

Follow Installation and Create a project, selecting Empty3d. Lua 5.4 is bundled; no external language tools or Rust build are required. Use a writable project and the default scene.

Arrange a floor and two cubes

1. In Project > Scene, open + Add and choose Rectangular Prism. Select it and set its name to Floor in Inspector. Set primitive dimensions to [20, 1, 20], Position to [0, -0.5, 0], and transform scale to [1, 1, 1]. Check Anchored and Can collide.
2. Add a Cube, name it Player, set Position to [0, 0.5, 0], and set unit size/scale. Check Anchored and Can collide. Anchoring prevents gravity competing with scripted movement.
3. Add another Cube named Box at [3, 5, 0]. Leave Anchored unchecked and check Can collide. No extra physics component is required for built-in primitives.
4. Use + Add > Camera if the scene has no camera. Navigate the authoring viewport until you see the floor and both cubes; select the camera and click Align to editor view in Inspector. Cameras look along local +Z. Ensure the camera is active; if multiple cameras are active, the highest priority is used.
5. Use File > Save scene.

Expected setup: a stationary floor, a player resting above it, a higher box and a game camera that can see all three. Viewport navigation explains framing and camera controls.

Create and attach your script

1. Select Player. Choose Programming > Object Component Script > Lua 5.4. Rustic creates a .lua asset and registers it with a stable ID.
2. Open it in your external editor through Programming > Open Project in Code Editor or Explorer. Replace its contents with the complete behavior below and save the file.
3. Confirm that the script is attached to Player and enabled in Inspector. If using an existing asset instead, select Player and use + Add Component to attach it. Avoid attaching the same controller twice.

local SPEED = 4.0

return {
  Start = function()
    rustic.log("info", "Player ready: hold WASD in the Play viewport")
  end,

  FixedUpdate = function(dt)
    local dx, dz = 0, 0
    if rustic.key("KeyA").held then dx = dx - 1 end
    if rustic.key("KeyD").held then dx = dx + 1 end
    if rustic.key("KeyW").held then dz = dz + 1 end
    if rustic.key("KeyS").held then dz = dz - 1 end
    local length = math.sqrt(dx * dx + dz * dz)
    if length == 0 then return end
    local x, y, z = rustic.get_translation()
    rustic.set_translation(x + dx / length * SPEED * dt,
                           y,
                           z + dz / length * SPEED * dt)
  end,

  OnStop = function()
    rustic.log("info", "Play stopped")
  end,
}

Start runs once for this behavior instance. FixedUpdate(dt) runs on simulation ticks and scales movement by elapsed time. Normalizing the direction prevents diagonal movement being faster. OnStop is the teardown callback; Stop and OnStart are not Lua lifecycle names. The owning object is the movement target, so there is no scene-name lookup in this controller.

Play and inspect the result

1. Press Play in the editor toolbar. Hover or click the embedded game viewport, then hold WASD.
2. The Console should show Player ready: hold WASD in the Play viewport. The player moves on the floor; Box falls and rests with its centre near Y = 0.5.
3. Use Pause and Frame Advance to inspect one fixed step. Resume to continue.
4. Press Stop. If the runtime-change review appears, choose Discard to keep your starting positions. Apply changes only when you deliberately want simulated transforms saved into the authored scene.

This controller teleports the anchored player and is not a swept character controller. It can pass through obstacles; it does not implement collision resolution or jumping. Keyboard forwarding currently works only in embedded Play for held WASD, arrows and Shift. New Window and Standalone do not forward these keyboard events.

Fix common mistakes

• No startup log: check .lua language, enabled attachment on Player, return { ... }, and Start spelling. Inspect the first Console error; a failed callback disables that instance.
• Log appears but no movement: hover/click embedded Play, use KeyW, and check that Player has the script. Moving the authoring camera is different from moving the player.
• Objects disappear: check the game camera and its orientation. Verify Floor is anchored and both floor/box have Can collide enabled.
• Player falls: check Anchored. The controller keeps its existing height; it does not override gravity.
• Cannot save: check the read-only indicator/project lock, project-directory permissions and Console diagnostics.

Fix and save script syntax errors, then restart Play for a clean run. Hot reload can retain the previous good behavior when new source fails validation; do not confuse that with running your latest edit.

Save the finished scene and run again

Stop, discard simulated changes, use File > Save scene, and save your .lua file. Close and reopen the project through Project Manager. Press Play and verify the startup message, player movement and falling box again. No downloadable sample is required or currently provided by the Not Yet Implemented examples repository.

Next steps

Read Lua input for arrows and sprinting, Physics for collider limits, Gameplay actions for tweens/timers, and Scripting scopes and execution. Playtesting and publishing explains the current boundary between running a scene and distributing a game.