Tally the Kills

The mission knows you need six kills. It will not tell you what a kill is worth, because to a mission every kill is worth exactly one sixth of a win. A score answers a different question: which run was better. It wants its own bucket.

        "SpaceShooterScore": {}

Names match, so the loader wires the System. Defaults are score: 0 and pointsPerKill: 100.

The whole component

/** The single-player run score. One per scene, on the world/director entity. */
export class SpaceShooterScoreComponent extends Component {
  score: number;
  pointsPerKill: number;

  constructor(data: Partial<SpaceShooterScoreInput> = {}) {
    super();
    const p = { ...DEFAULT_SPACE_SHOOTER_SCORE_PARAMS, ...data };
    this.score = p.score;
    this.pointsPerKill = p.pointsPerKill;
  }

  serialize(): SpaceShooterScoreInput {
    return {
      score: this.score,
      pointsPerKill: this.pointsPerKill,
    };
  }
}

A number you add to and a number you multiply by. There is no list of kills, no per-enemy breakdown, no combo timer. A scoreboard that renders one integer needs one integer.

The name is doing a job. There is already a Score component in the library, the generic per-player one that listens for score.add and goal.scored. This one counts ship kills. Every component in the marketplace shares one flat namespace, so a variant is named for the subgenre it belongs to rather than stealing the bare name from the general case.