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Twitch·Software Engineer·Technical Phone Screen·Intermediate

Intermediate
May 2026

Summary

Twitch software engineer interview that centered on a classic game design problem with enough follow-ups to keep you on your toes. The core question was straightforward but the extensions pushed into real OOP territory pretty fast.

Questions Asked (1)

Q1

Design and implement a Rock-Paper-Scissors game for two players, then extend it with a streak-based bonus points system and a tie-break rule that guarantees a definite winner. Be prepared to walk through your class design and how you'd scale it to more players or new move types.

System DesignTechnical Trade-offsAlgorithms & Data Structures
Author's notes

I started with a simple match loop and a result enum, which felt fine, but the streak multiplier tripped me up a bit.

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AI HintsAI Generated

Suggested Approach

Start by clarifying requirements and defining the core entities (Player, Move, Game) with clean interfaces, then implement the basic game loop with a rules engine. Extend with a streak bonus system and a deterministic tie-break rule, ensuring the design remains extensible for more players and move types. Discuss trade-offs and scalability throughout.

Pro tip: Emphasize extensibility: use a strategy pattern for move resolution and a plugin-like registry for new moves, so adding moves or players doesn't require modifying core logic. Also, mention how you'd handle concurrency if scaling to many players.

1. Clarify Requirements and Constraints

Ask about expected number of players, move types, persistence, and whether the game is real-time or turn-based. Confirm the tie-break rule and streak bonus details.

2. Design Core Classes and Interfaces

Define Player, Move, Game, and a RulesEngine interface. Use enums or classes for moves and a resolver that determines the winner between two moves.

3. Implement Basic Game Logic

Code the game loop: collect moves, resolve winner, update scores. Ensure the tie-break rule is applied when moves are equal, and streak bonuses are tracked per player.

4. Extend for Scalability

Refactor to support N players and new move types. Use a registry for moves and a tournament-style resolution for multiple players.

5. Discuss Trade-offs and Testing

Talk about time/space complexity, potential concurrency issues, and how you'd test edge cases like ties and streak resets.

Key Points to Mention

  • Use of strategy pattern for move resolution to allow easy addition of new moves.
  • Streak bonus implementation: track consecutive wins per player and apply multiplier.
  • Tie-break rule: e.g., sudden death or predetermined priority, ensuring a winner.
  • Scalability to N players: round-robin or bracket system, and move registry.
  • Concurrency considerations if multiple games run simultaneously.
  • Testing: unit tests for rules, streak logic, and tie-break scenarios.

AI-generated suggestions, not part of the candidate's original notes. May be inaccurate — verify before relying on them.