Here is the full list of all 20 The Brookhaven Experiment achievements.
Acquire 200 throwables in campaign mode.
Blow the head off of something large and toothy.
Acquire all guns and upgrades in a survival game.
Survive the final campaign level.
Survive the ninth campaign level.
Survive the eight campaign level.
Survive the sixth campaign level.
Survive the fifth campaign level.
Survive the fourth campaign level.
Survive a nighttime campaign level using only the knife.
Survive the second campaign level.
Finish a nighttime campaign level without turning on the flashlight.
Survive the third campaign level.
Acquire all guns and upgrades in campaign mode.
Survive the first campaign level.
Survive the seventh campaign level.
Survive ten waves in a survival map.
Kill four enemies at once with an explosive.
Kill 1000 enemies.
Kill 100 enemies.