At least one runbook exists for the planned failure mode so the game day can test instructions.
Game Day
Prerequisite
What needs to be finished first
Incident roles (commander, communicator, operator) are established so the exercise runs realistically.
Preparation
What needs to be ready before start
Failure-injection tools (Chaos Mesh, Gremlin, AWS Fault Injection Simulator); observability stack (Datadog, Grafana, logs); communication channel; scenario and expectation script; safety shutoff.
A game day master (script author); incident commander; operator team; observer for each relevant service; stakeholder representative; safety officer with abort authority.
Architecture diagram; SLO/SLA of affected services; known weaknesses from past incidents; current runbooks; pre-test health check.
4-8 h for a game day, plus 1-2 weeks preparation
Schedule date in calendar and inform all relevant stakeholders. Production mode: failure injection on staging or isolated tenant. Define safety abort conditions (big red button). Establish communication plan so real users are not startled.
Core question
The one question this method answers
How do system, tools, and team react to realistically injected failures, and which gaps in runbooks, monitoring, or roles become visible?
Flow
Marker: Phase
| Step | Duration | Action | Hint |
|---|---|---|---|
1Phase 1: Script and hypotheses | 3-5 days lead time | Define three to five scenarios (for example DB failover, pod crash, region outage). For each scenario define hypothesis, expected result, and success criteria (for example recovery in 5 min). | Write hypothesis explicitly. If no one states expected behavior before start, no surprise can be learned. |
2Phase 2: Setup and safety brief | 30 min | Verify observability stack. Assign roles. Clarify Big Red Button criteria (for example real customer impact above threshold X). Communicate to stakeholders. | If stakeholders are not informed, a real alert can trigger escalations outside the exercise. Clear labeling is required. |
3Phase 3: Injection and response | 2-4 h | Scenario by scenario: inject failure, team responds with runbook, observers log response times, decisions, and tool behavior. Game day master delays recovery when appropriate. | Maintain realism. When participants know it is an exercise, adrenaline drops. Still, avoid too long delays to prevent frustration. |
4Phase 4: Recovery and verification | 30-60 min | After each scenario, team performs controlled recovery. Observers check whether monitoring detected the failure and runbook worked. | Recovery is part of the exercise. If recovery fails, the runbook has a gap. When complete standby outage happens, safety officer triggers Big Red Button. |
5Phase 5: Debrief and follow-ups | 60-90 min | Run after-action review per scenario: plan vs reality, root causes, lessons, actions. Create tickets with owner and deadline for top-3 lessons. Plan runbook updates. | Lessons without follow-up waste the game day. Limit to three actions per game day, otherwise follow-through disappears. |
Artifact
What comes out at the end
Game day report with scenarios, hypotheses, response metrics (time to detect, time to mitigate), observations, lessons learned, and action list with owner and deadline.
One entry per game day with date, scenarios, and outcomes. Compare across game days (time-to-detect and time-to-mitigate trends). Link runbook versions before and after game day.
- Gremlin or Chaos Mesh for failure injection
- AWS Fault Injection Simulator, Azure Chaos Studio
- Custom scripts with Toxiproxy or iptables
- Confluence or Notion report with attachments (logs, screenshots)
- PagerDuty drill mode for realistic alerting
game-day-working-template.md
Compact working template for Game Day with context, input, output artifacts, and next step.
Game Day Working Template
Goal
A realistic exercise to practice incident response and recovery.
Context
When and for what do we use this method?
Input
Which data, observations, decisions, or materials are available?
Execution
Short notes along the runsheet.
Output artifacts
- Simulation Notes:
- Gaps List:
- Updated Runbooks:
Assumptions and open questions
- ...
Decision / Next step
Owner, date, and success signal.
Example output
Concrete filled scenario, fictional example
game-day-beispiel.md
Concrete filled scenario, fictional example
Game Day - Platform team Workspot, 15.05.2026
Participants: Game Day Master @lisa, Incident Commander @ben, Operator (3 engineers), Observer (2 SREs), Safety Officer @marcus.
Scenarios
- DB primary failover.
- CDN region outage (eu-central).
- Auth service 100% 5xx for 10 min.
Hypotheses
- Scenario 1: Recovery in <3 min via auto failover.
- Scenario 2: Failover to eu-west via DNS in <5 min.
- Scenario 3: Runbook RB-AUTH-01 leads to mitigation in <10 min.
Results
| Scenario | Time-to-detect | Time-to-mitigate | Hypothesis met |
|---|---|---|---|
| 1 DB failover | 0:42 | 2:18 | Yes |
| 2 CDN outage | 1:54 | 14:30 | No (DNS TTL 300 s, manual switch required) |
| 3 Auth 5xx | 0:28 | 4:50 | Yes, runbook worked |
Top lessons
- CDN DNS TTL is 300 s and blocks failover. Lower to 60s.
- Auth runbook worked reliably with cycle time within limit.
- Observer tool reported CDN outage only after 1:54 (polling interval 60 s).
Actions
- GD-01: Reduce CDN DNS TTL to 60 s. Owner: @marcus, by 22.05.
- GD-02: Reduce CDN health-check polling to 15 s. Owner: @lisa, by 29.05.
- GD-03: Make a quarterly drill standard at 2x per quarter. Owner: @ben.
Pitfalls
Recognize symptoms and steer against them
Game day in production without safeguards
Real users are affected, complaints escalate, and trust is damaged.
Start in staging, then isolated production tenant, and only then full production. Use safety officer and big red button before every injection.
No hypotheses beforehand
Team "just watches" without expected behavior, so surprises are missed.
Write hypotheses before start. State expectations in advance. Deviation from hypothesis is the primary learning signal.
Lessons not implemented
Three game days produce the same lessons (for example slow monitoring), without change.
Cap three actions, with owner and deadline. Quarterly review expectation: close old actions before adding new ones. Otherwise stop.
Stakeholders not informed
Real alert triggers and escalates to leadership while the team is practicing.
Define communication plan: inform all relevant stakeholders (support, sales, leadership) before. Mark alert channels (for example [DRILL]) clearly.
Too many scenarios
Seven scenarios in 4 hours, no debrief, lessons blur together.
Maximum three scenarios per 4-hour game day. Debrief directly after each scenario. Use realistic cycle times.
No observers
No one logs response times, so debrief depends on memory.
At least one observer per scenario with timer and notes template. Response metrics must be facts, not anecdotes.
Stop criteria
Done signals checkable in under a minute
Finished the runsheet?
Go to the profile for purpose, similar methods, and sources or continue to the next method in the catalog.