How do you track down a bug that only happens rarely, like once in fifty playthroughs?

What the interviewer is looking for

• This question tests debugging & tools. Reproduces rare bugs methodically using logging, replays and debug views, and builds tools that speed up the team.
• Strong answers: Gathering reports and logs, adding targeted logging or assertions, recording inputs or replays, fixed seeds, stress testing, and forming hypotheses about timing or physics.
• Likely follow-up: How would you confirm the fix when you can't reliably reproduce it?

Another way it may be asked: Testers say a character sometimes falls through the floor, but nobody can make it happen on purpose. What do you do?

A structure to follow: Answer, explain, example, limits

1. Step 1

   Answer

   Give your direct answer in the first sentence so the interviewer knows where you are going.

2. Step 2

   Explain

   Say how it works or why you would do it that way, in plain words before jargon.

3. Step 3

   Example

   Anchor it in something you have actually done or seen, with the detail that shows hands-on experience.

4. Step 4

   Limits

   Say when your approach would not be the right one. It shows judgement.

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

• Reciting a definition without showing you have applied it.
• Using terms you cannot explain if asked a level deeper.
• Claiming experience beyond what you can discuss in detail.

How to practise it

Say the answer in 90 seconds, then answer the follow-up as if it were a new question.

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