Find an area that contains a working slot machine. For example, in the Siren Alley level inside the Mermaids Lounge, go upstairs into the room on the right side of the balcony that contains the slot machines. As you enter the room, turn left, and play the right-hand machine of the two that are facing you. Save the game before you start, and resave it every time your total money increases above where you started. If the machine does not payout after about a dozen turns, reload your saved game. It is possible to max out your wallet in approximately ten minutes. Repeat this as many times as desired.

Find a hackable vending or health machine next to or near a Bot Shutdown Panel. Hack the machine, and stop the pointer on the red to activate the alarm, thus triggering the Security Bots to come after you. Once you see them, quickly take a picture of one of them with the camera, then use the Bot Shutdown Panel to shut them down. The disabled bot will still be highlighted by the research camera, allowing you to research Security easily.

Have a friend join your game while it is in progress on any team-based game, putting him or her on the other team. Find a turret anywhere in the map, and make sure there is nobody around. You and your friend can hack the turret back and forth for 10 XP per hack. Repeat this as many times as desired. -From: Christian Manzi

Successfully complete the indicated tasks to get the corresponding ending. There are six different endings: Rise To Surface (good and evil), Abandoned (good and evil), and the standard ending (good and evil).

Good endings

Save all Little Sisters you adopt, and spare Grace Holloway, Stanley Poole, or Gilbert Alexander.

Save all Little Sisters you adopt, and kill Grace Holloway, Stanley Poole, and Gilbert Alexander.

Standard endings

Save at least one Little Sister, and harvest at least one Little Sister. Choose to die at the end, and spare Grace Holloway, Stanley Poole, and Gilbert Alexander.

Save at least one Little Sister, and harvest at least one Little Sister. Choose to die at the end, and kill Grace Holloway, Stanley Poole, or Gilbert Alexander.

Bad endings

Save at least one Little Sister, and harvest at least one Little Sister. Choose to live at the end, and spare Grace Holloway, Stanley Poole, and Gilbert Alexander. Alternately, harvest all Little Sisters you adopt, and spare Grace Holloway, Stanley Poole, and Gilbert Alexander.

Save at least one Little Sister, and harvest at least one Little Sister. Choose to live at the end, and kill Grace Holloway, Stanley Poole, or Gilbert Alexander. Alternately, harvest all Little Sisters you adopt, and kill Grace Holloway, Stanley Poole, or Gilbert Alexander.

Use the following trick to pull normal items toward you with Telekinesis and not use any Eve. Eve is only used when you release the button to throw an item with Telekinesis. Use Telekinesis to pull items such as ammunition or first aid kits toward you to collect without wasting any of your Eve. If you take an item you are already maxed out of, you will either be stuck holding it with Telekinesis or have to release the button to throw it and use some Eve. However, if you display the Plasmid wheel and select another Plasmid attack, you can release the button to drop the item without Telekinesis automatically throwing it. Thus, you will not use any Eve by dropping an item you cannot carry. This can also be used when pulling electrified trip wires out of walls. To do this, pull the item toward you with Telekinesis, and without releasing the trigger, display the Plasmid wheel to select another plasmid. When you close the Plasmid wheel and release the trigger, you will drop the item.

When fighting a Rumbler (Big Daddy with rockets), use Telekinesis to grab the rockets it fires and throw them back at it.

Power To The People weapon upgrade stations can be found at the following locations:

1. Ryan Amusements: Going to get the ticket.
2. Ryan Amusements: After the family display, through the door.
3. Pauper's Drop: From Journal 039, go out the door, down the stairs.
4. Pauper's Drop: In the back of skid row, in the limbo room. It is behind the stage
5. Pauper's Drop: After breaking into the hotel, when you are going through the halls, you will go through a hole. To the left is a blue sheet. To the right is the station.
6. Siren Alley: In Mermaid Lounge, go upstairs, and hack the gate. Then, drop through a hole in the floor.
7. Siren Alley: Just before Pump Station 5.
8. Dionysus Park: Behind the door; combination is 1080.
9. Dionysus Park: On the path to the train.
10. Fontaine Futuristics: After you destroy the flying Gil bot, you can enter where you gain access to the laboratory.
11. Fontaine Futuristics: After you turn on the lights, it will be in the bottom of the holding cells area.
12. Persephone Outer: On your left.
13. Inner Persephone: After you gain access to Sinclair, look back in the room.
14. Inner Persephone: Just after Ward B in the room with the rocket turret.

Accomplish the indicated achievement to get the corresponding number of Gamerscore points:

Bought a Slot (5 points): Buy one Plasmid or Tonic Slot at a Gatherer's Garden.
Max Plasmid Slots (10 points): Fully upgrade to the maximum number of Plasmid Slots.
Upgraded a Weapon (10 points): Upgrade any weapon at a Power to the People Station.
Fully Upgraded a Weapon (10 points): Install the third and final upgrade to any of your weapons.
All Weapon Upgrades (20 points): Find all 14 Power to the People weapon upgrades in the game.
Prolific Hacker (20 points): Successfully hack at least one of every type of machine.
Master Hacker (20 points): Hack 30 machines at a distance with the Hack Tool.
First Research (5 points): Research a Splicer with the Research Camera.
One Research Track (20 points): Max out one Research Track.
Research Master (20 points): Max out research on all 9 research subjects.
Grand Daddy (25 points): Defeat 3 Big Daddies without dying during the fight.
Master Gatherer (30 points): Gather 600 ADAM with Little Sisters.
Fully Upgraded a Plasmid (10 points): Fully upgrade one of your Plasmids to the level 3 version at a Gatherer's Garden.
All Plasmids (20 points): Find or purchase all 11 basic Plasmid types.
Trap Master (15 points): Kill 30 enemies using only Traps.
Master Protector (15 points): Get through a Gather with no damage and no one getting to the Little Sister.
Big Spender (15 points): Spend 2000 dollars at Vending Machines.
Dealt with Every Little Sister (50 points): Either Harvest or Save every Little Sister in the game.
Against All Odds (30 points): Finish the game on the hardest difficulty level.
Big Brass Balls (25 points): Finish the game without using Vita-Chambers.
Rapture Historian (40 points): Find 100 audio diaries.
Unnatural Selection (10 points): Score your first kill in a non-private match.
Welcome to Rapture (10 points): Complete your first non-private match.
Disgusting Frankenstein (10 points): Become a Big Daddy for the first time in a non-private match.
"Mr. Bubbles - No!" (20 points): Take down your first Big Daddy in a non-private match.
Mother Goose (20 points): Save your first Little Sister in a non-private match.
Two-Bit Heroics (10 points): Complete your first trial in a non-private match.
Parasite (10 points): Achieve Rank 10.
Little Moth (20 points): Achieve Rank 20.
Skin Job (20 points): Achieve Rank 30.
Choose the Impossible (50 points): Achieve Rank 40.
Proving Grounds (20 points): Win your first non-private match.
Man About Town (10 points): Play at least one non-private match on each multiplayer map.

Additionally, there are seventeen secret achievements:

Daddy's Home (10 points): Found your way back into the ruins of Rapture.
Protector (20 points): Defended yourself against Lamb's assault in the train station.
Sinclair’s Solution (20 points): Joined forces with Sinclair in Ryan Amusements.
Confronted Grace (10 points): Confronted Lamb’s lieutenant in Pauper’s Drop.
Defeated the Preacher (20 points): Defeated the Preacher.
Nose for News (20 points): Uncovered the secret of Dionysus Park.
Found Lamb's Hideout (20 points): Gained access to Lamb’s stronghold.
Reunion (50 points): Reunited with your original Little Sister.
Heading to the Surface (25 points): Headed to the surface on the side of Sinclair's escape pod.
Escape (100 points): Escaped Rapture.
9-Irony (5 points): Paid your respects to the founder of Rapture.
Distance Hacker (5 points): Used the Hack Tool to hack an object at a distance.
Unbreakable (20 points): Defended yourself against the Big Sister without dying.
Look at You, Hacker (15 points): Killed 50 enemies using only hacked Security.
Adopted a Little Sister (5 points): Adopted a new Little Sister for the first time.
Savior (25 points): Saved every Little Sister and spared Grace, Stanley and Gil.
Counterattack (5 points): Killed an enemy with its own projectile.