call_other_class_method_example.ts

//ball.ts
import { Mesh} from "@babylonjs/core";
import GameComponent from "./game";

export default class BallComponent extends Mesh {

    public _scene: GameComponent;
    //...
     /**
     * Called each frame.
     */
    public onUpdate(): void {
        this.position.y = this._startHeight;

        if (this.position.x < -30) {
            this._scene.retry();
        }
    }
    //...
}

//game.ts      
////.....
import { Scene } from "@babylonjs/core";
export default class GameComponent extends Scene {
     ///... 
     /**
     * THe player lose, let's retry :)
     */
    public retry(): void {
          // do something..
    ///...      
    }
                             
}