Full list of all 10 Outbreak: The New Nightmare Definitive Edition achievements worth 1,000 gamerscore.
Restore your health with a healing item.
Heal yourself 25 times.
Clear a wave in Onslaught.
Fail to survive.
Kill an undead threat.
Kill 100 undead threats.
Kill 1250 undead threats.
Land 20 critical hits.
Clear a non-tutorial campaign scenario on Biohazard difficulty.
Clear a non-tutorial campaign scenario on Nightmare difficulty.