Ammo Inventor (25) Successfully invented all possible ammo types.
Avid Inventor (10) Successfully invent at least 100 items.
Basic Inventor (5) Successfully invent at least one item.
Became a Big Daddy (30) The player has become a Big Daddy.
Bought One Slot (5) Purchase one slot in any Plasmid or Tonic track.
Broke Fontaine's Mind Control (30) The player has broken Fontaine's mind control.
Completed Cohen's Masterpiece (30) The player has completed Sander Cohen's great masterpiece.
Completed Welcome (10) Successfully complete the Welcome To Rapture Level.
Dealt with every Little Sister (40) Either Harvest or Rescue every Little Sister in the game.
Defeated Andrew Ryan (30) The player has defeated Andrew Ryan.
Defeated Atlas (100) The player has defeated Atlas.
Defeated Dr. Steinman (15) The player has defeated the crazed Dr. Steinman.
Defeated Peach Wilkins (15) The player has defeated Peach Wilkins.
Five Fully Upgraded Weapons (10) Fully upgrade five weapons.
Found Cohen's Room (10) The player has entered Sander Cohen's personal quarters.
Four Fully Upgraded Weapons (10) Fully upgrade four weapons.
Fully Researched Bouncer (10) Fully research the Bouncer.
Fully Researched Gun Splicer (10) Fully research the Leadhead Splicer.
Fully Researched Houdini Splicer (10) Fully research the Houdini Splicer.
Fully Researched Little Sister (10) Fully research the Little Sister.
Fully Researched Nitro Splicer (10) Fully research the Nitro Splicer.
Fully Researched Rosie (10) Fully research the Rosie.
Fully Researched Spider Splicer (10) Fully research the Spider Splicer.
Fully Researched Thug Splicer (10) Fully research the Thuggish Splicer.
Hacked a Safe (10) Successfully hack a safe.
Hacked a Security Bot (10) Successfully hack a security bot.
Hacked a Security Camera (10) Successfully hack a security camera.
Hacked a Turret (10) Successfully hack a turret.
Hacked a Vending Machine (10) Successfully hack a vending machine.
Historian (50) Find every audio diary.
Irony (10) The player has taken a picture of Sander Cohen's corpse.
Little Sister Savior (100) Complete the game without harvesting any Little Sisters.
Lucky Winner (10) Hit the jackpot at a slot machine.
Maxed All Tracks (50) Purchased every slot in all four Plasmid and Tonic tracks.
Maxed One Track (20) Purchased every slot in one of the Plasmid or Tonic tracks.
One Fully Upgraded Weapon (5) Fully upgrade one weapon.
One Successful Hack (5) Perform at least one successful hack.
Prolific Photographer (5) Take at least one photo in every research group.
Quality Research Photo (20) Take a Research Photo of the highest grade.
Research PhD (20) Max out all possible research.
Researched a Splicer (5) Take at least one Research Photo of a Splicer.
Restored the Forest (15) The player has restored the forests of Arcadia.
Seriously Good At This (40) Complete the game on the hardest difficulty setting.
Skilled Hacker (40) Successfully complete 50 hacks.
Three Fully Upgraded Weapons (10) Fully upgrade three weapons.
Toaster in the Tub (10) Shock an enemy in the water.
Tonic Collector (50) Collect or Invent 53 Tonics in the Physical, Engineering and Combat tracks.
Two Fully Upgraded Weapons (5) Fully upgrade two weapons.
Upgraded a Weapon (5) Acquire at least one weapon upgrade.
Weapon Specialist (20) Acquire all upgrades for all weapons.
About halfway through the game, you meet Sander Cohen, this crazy artist dude. When you finish the level, you can just leave him or kill him. If you kill him at that point, you can't get one of the Achievements "Find Cohen's Room." A while later you will stumble onto Cohen's apartment. If he's alive, two Splicers will be dancing in the main room, with Cohen watching from his locked private room. Kill the Splicers and then Cohen comes out to fight you, thus unlocking the door and allowing you to earn the Achievement.
In order to do this, you need the Hypnotize Big Daddy Plasmid and the Natural Camouflage Tonic. All you have to do is use the Hypnotize Big Daddy Plasmid on a Big Daddy so that he thinks you're a Little Sister and protects you. Now here's the fun part - simply find and attack another Big Daddy and your Big Daddy will attack it to protect you.
