Full list of all 10 Outbreak: Epidemic achievements worth 1,000 gamerscore. It takes around 0.5-1 hour to unlock all of the achievements on Xbox One.
Cleared Onslaught Mode on any scenario and difficulty.
Defeated a Brute
Defeated an Enforcer.
Defeated a Reptile.
Cleared a Campaign Scenario on Easy Difficulty or Higher.
Cleared a Campaign scenario on Nightmare Difficulty.
Cleared a Campaign scenario on Normal Difficulty or Higher.
Cleared a Campaign scenario on Biohazard Difficulty or Higher.
You died.
Defeated a Zombie.