In the Eternal flame crematorium there is a corpse in the furnace slide. If you push the green button that indicates furnace control the body will be cremated. When the slide comes out there will be a gene tonic for hacking.
If you take pictures of Houdini splicers you will receive a special plasmid it's called natural camouflage. There are a few limitations to this ability. You have to stand still. It takes a couple of seconds. You can't open fire on a splicer and stay invisible. If a splicer sees you you can't turn invisible. But think of it turrets, splicers, security cameras, and even big daddy wont be able to see you.
If your running low on health kits go to a health station. Hit the health station with your wrench. Once it breaks down it will give you one kit.The health stations will sometimes give you three kits. Breaking health stations is the best thing to do. Hacking one is to difficult and use a automatic hacking tool is a waste. Splicers love to go to them once there low on life.
There is a secret trophy you can get if your in Olympus Heights. Go to Sander Co-hen's room.Kill both of the splicers that are dancing. Be careful their Houdini splicers. Once you kill them both Sander Cohen will be mad he will appear in his room. He is pretty hard to kill. An easy way to kill him is to use the enrage plasmid on a big daddy. Once Sander Cohen is dead take a picture of him. The trophy is an irony trophy.
The door code am going to give out are 0126, 7549, 0512,and 7533. O126 is Kyburz's office door code in Hephaestus. 7539 I don't remember what it's for but it is a door code.0512 is the door code for a locked room in Arcadia somewhere in the farmers market. 7533 is the code for a room in the fighting McDonald's. All lock rooms have good ammunition for important weapons.