I own this game and have beaten it many time. Tere aren't really cheats but this might help. The only cheats are the codes to the doors requiring a password. Here you go........
Restoring hacked robot's health
After hacking a robot, it will begin firing at your enemies. If the robot gets hit, it will begin to lose health, catch on fire, and eventually blow up. To stop this from happening, deactivate the robot (press A while pointing at the robot), then reactivate it a few seconds later. This should make the robot have full health again.
Hitting the jackpot at slot machine
Save the game before you start playing the slot machine. Then, keep reloading your saved game until you hit the jackpot.
Easy money
Use the Incinerate Plasmid on any slot machine to corrupt the machine. You will usually always win money when you use the burnt out machine.
Molotov cocktails
While normally the various alcoholic beverages (for example, Arcadia Merlot, Old Tom Whiskey, etc.) scattered throughout the game are used to recover health, they can be turned into Molotov cocktails similar to those used by the "Nitro Splicer" enemy. To do this, use a source of flame, such as the chemical thrower, the Incinerate! Plasmid, or an environmental source. Ignite the alcohol bottle, pick it up with the Telekinesis Plasmid, and throw it at the enemy of choice.
Save game recommendations
Save the game before fighting a Big Daddy or other difficult enemies. If you do not like the results (used too much health, wasted too much ammunition, etc.), you can simply reload your saved game and try again until you are satisfied.
After becoming a Big Daddy, create a new saved game. At this point, you will be close to the end of the game. If you missed something, you can go to the Bathysphere and explore Rapture again; you are also a Big Daddy now so the Splicers will not harm you, security cameras will not set off alarms, etc.
Tonic locations
Medical Pavilion
1. Security Expert: On a shelf in the Twilight Fields mortuary.
2. Speedy Hacker: In the corner of Painless Dental.
3. Wrench Jockey: In Kure All, through the crawl shaft on the floor.
4. Hacker's Delight: Activate the furnace in the Eternal Flame Crematory.
5. Static Discharge: In the Surgery Foyer next to Steinman's lab.
6. Eve Link: Purchased at Gatherer's Garden
7. Armored Shell: Purchased at Gatherer's Garden
Neptune's Bounty
8. Wrench Lurker: Lower Wharf, near the edge of the walkway (after you get the camera.).
9. Focused Hacker: Inside Fontaine Fisheries, next to first pneumo tube.
10. Medical Expert: On the lower Wharf as you enter the level.
11. Extra Nutrition: Purchased at Gatherer's Garden
Arcadia
12. Security Evasion: On the lower left area of Arcadia. It will be next to a dead Houdini Splicer that is surrounded by four Thuggish Splicers.
13. Hacking Expert: On the desk as you enter the Research Laboratories.
14. Shorten Alarms: Purchased at Gatherer's Garden
15. Human Inferno: Purchased at Gatherer's Garden
Farmer's Market
16. Eve Link 2: To the left of the entrance, near the Circus Of Value and U-Invent machine
17. Photographers Eye: In the bunk of the bottom floor of the winery.
Fort Frolic
18. Alarm Expert: On the balcony of the fleet Hall. Jump to it from the balcony next to it.
19. Frozen Field: Search Matin Finnegan's corpse.
20. Extra Nutrition 2: Down the stairs behind the main stairway of the main atrium near Eve's Garden.
21. Electric Flesh: In Cohen's dressing room. Must complete his masterpiece, then go to the room next to the upstairs projection booth.
22. Medical Expert 2: Unlocked by Sander after you complete his masterpiece.
23. Hacking Expert 2: Purchased at Gatherer's Garden
24. Bloodlust: Must be invented in the U-Invent machine
25. Booze Hound: Must be invented in the U-Invent machine
26. Hacker's Delight 2: Must be invented in the U-Invent machine
Hephaestus
27. Frozen Field 2: On a desk in the bottom corner of the central core.
28. Security Evasion 2: In Lower Heat Loss Monitoring on a desk.
29. Damage Research: Secret crawlspace in the back of the lower workshops.
30. Shorten Alarms 2: Geothermal core (after you deploy the bomb).
Olympus Heights
31. Clever Inventor: On a desk in Suchong's Apartment.
32. Electric Flesh 2: On a desk in Fontaine's Apartment.
33. Speedy Hacker 2: Purchased at Gatherer's Garden
34. Wrench Lurker 2: Purchased at Gatherer's Garden
Apollo Square
35. Medical Expert 3: Second floor of Suchong's clinic.
36. Focused Hacker 2: Fourth floor of the Hestia building.
Point Prometheus
37. Safe Cracker 2: Autopsy room of the first floor of Little Wonders.
38. Alarm Expert 2: On a filing cabinet in Point Prometheus.
39. Damage Research 2: On a desk in the second floor library.
40. Hacker's Delight 3: Next to Rosie helmets in Failsafe Armory.
41. Human Inferno 2: Purchased at Gatherer's Garden
Tenenbaum Gifts
42. Safecracker: Rescue 6 Little sisters.
43. Armored Shell 2: Rescue 15 Little sisters.
44. Prolific Inventor: Rescue 18 Little sisters.
Research Bonuses
45. Natural Camoflage: Research level 2 Houdini Splicers.
46. Scrounger: Research level 2 Leadhead Splicers.
47. Sportboost: Research level 2 Thuggish Splicer.
48. Photographer's Eye 2: Research level 2 Rosie.
49. Wrench Jockey 2: Research level 2 Bouncer.
50. Extra Nutrition 3: Research level 4 Spider Splicer.
51. Sportboost 2: Research level 4 Thuggish Splicer.
52. Static Discharge 2: Research level 4 Leadhead Splicer.
53. Security Expert 2 : Research level 2 Security Bot.
Weapon Upgrade Station locations
1: In Peach Wilkins' hideout (Neptune's Bounty), bottom floor. As soon as you come downstairs, it is directly in front of you.
2: On the way to Farmer's Market in Arcadia, the station is located to the left after you go up the first stairs coming from Tree Farm.
3: Go to Winery's basement in Farmer's Market. There is a flooded area with one of them attached to the wall. It is in front of you when you come down the stairs; just keep going forward.
4: In Fort Frolic, from the Atrium bottom floor, go towards the bathrooms. Then, move right and follow the path until you see some small stairs to your right leading up to a door. Go inside, then go down into the basement. The basement is filled with cigars and other stuff. The upgrade station is on the wall.
5: Go to Poseidon Plaza in Fort Frolic. Go to the other end of the bottom floor (the opposite end of where you enter). Go into Sinclair Spirits (the room that has a corpse on a sort of "altar"). In the basement of this store is the station.
6: In Hephaestus Core Room, go down to the bottom floor, and run around (literary). Eventually you will see it attached to the wall.
7: In Hephaestus, Kyburz's office. It is attached to the left wall (back turned to the entrance) in the rear of the room.
8: At the bottom floor of the Mercury Suites area, on the back of the center pillar.
9: In Sander Cohen's secret room, in the Olympus Heights' Mercury Suites area.
10: Go to Atlas' Headquarters in Apollo Square (Fontaine's Home For The Poor area). It is located on the fourth floor. Go down the stairs in the room and look to the right. The station will be in front of you.
11: When you enter Point Prometheus and chase Fontaine, eventually you will end up in a little square, and Fontaine will go behind a locked Museum door. At the opposite end of this square (from where you came) is a dead Big Daddy. Next to it is the upgrade.
12: In the Voice changing labs in Point Prometheus, one of the labs has it.
Easy kills
When you start, you will have the Wrench and the Electric Bolt Plasmid. Using these in rapid succession against most Splicers can often result in an efficient, quick kill. First, shock the Splicer. Before the convulsion ends, switch to the wrench, aim high, and hit the Splicer over the head. An efficient way of killing the Spider Splicers is to shoot a few clips of anti-personnel ammunition, preferably from the machine gun.
Finding Chompers' Dental key
The key to Chompers' Dental in the Medical Pavilion is acquired by using Telekinesis through the broken window to the left of the door. There should be a corpse hanging over the broken window. The key should be grabbed with Telekinesis because it is hanging on a wall on the other side of the window. You can get Telekinesis in an area near here. You will need to get that first, but do not follow the arrow back to the rubble that you need to get rid of until you explore Chompers' Dental. There is a safe and other good items inside. Note: Both Telekinesis and Chompers' Dental are near where you find the shotgun.
Reaching Atlas Fontaine's penthouse
The code to get to Atlas Fontaine's penthouse is "5744", which is in an Audio Diary.
Defeating Atlas Fontaine
Atlas Fontaine, the the final Boss, has three different styles of attacks: Flame Plasmid, Ice Plasmid, and Electric Plasmid Form. An easy way to defeat him in the first part is to use your Ice Plasmid and freeze him. Then, switch to your Telekinesis Plasmid. Grab an explosive tank, and throw it at him. Also, if desired, just use your telekinesis. He is very predictable if you are far away from him. Wait for him to throw a fire ball at you, then move out of the way. He will continue to run past you. Use this chance to fire the machine gun, which does the most damage to him. Once he goes back to his chamber to gain his life back, change to the Flame Plasmid, and get ready for some bots. Once he starts his routine of fire and run, shoot him with the Flame Plasmid as many times as possible. Continue to use