When would you build a custom system rather than use what the engine already provides? Tell me about a time you made that call.

What the interviewer is looking for

• This question tests game engine proficiency. Speaks fluently about a major engine's architecture, tools and limits, with examples of shipped or substantial projects.
• What to bring out: Clear reasons such as performance or design needs, cost of maintenance and upgrades, prototyping first, and an honest outcome.
• Expect a follow-up like: Looking back, was it worth it?

Another way it may be asked: The engine's built-in pathfinding isn't quite right for your game. How do you decide whether to extend it or write your own?

A structure to follow: STAR, with the weight on Action and Result

1. Step 1

   Situation

   One or two sentences: where, when and what was at stake. Pick a real example you were close to.

2. Step 2

   Task

   What you personally were responsible for. Say "I", not only "we", so the game engine proficiency you showed is visible.

3. Step 3

   Action

   The two or three things you did and why you chose them over the alternatives. This should be about half your answer.

4. Step 4

   Result

   What changed, in your own measure of it, and what you would do differently. Only use numbers you can stand behind.

This is guidance on shape, not a script. Use your own real experience and facts; never invent details to fill a gap. See the STAR guide and answer frameworks.

Common slips

• Describing what the team did without saying what you did.
• Choosing an example with no clear outcome, or one you cannot answer detailed questions about.
• Ending on the action and skipping the result and what you learned.

How to practise it

Write two bullet points for each STAR letter, then say the answer aloud in about two minutes.

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