1. Complete Level 5: Reach the end of Level 5 in the World Tour.
2. Build a Bunker: Construct a Bunker in your Infection Menu by spending 500 DNA in the "Facilities" section.
3. Research Project Alpha: Start researching Project Alpha in your Infection Menu. This requires 100 DNA and 10 minutes to complete.
4. Complete Research: Wait for Project Alpha to finish.
5. Unlock the Boomer: Once the research is complete, you will automatically unlock the Boomer.
The Boomer is a powerful and unique infected that can spread the virus through explosions and has a high chance of causing Panic in humans. Its Special Ability, "BOOM!", creates a 3x3 area of effect around the infected that deals damage and infects nearby humans.