Entering the Amusement Park
To enter the amusement park, go along the docks until you come to the ruined part of the pier. Get up by climbing to the level part, and start walking to the gate. If you reach the gate before Diana's done briefing you, then the info bar will tell you to "Wait for the Guard". Either way, after the guards inquiries, Agent 47 will use his head to open the gate.
Gift Shop and Theater
The game will now tell you to examine the picture of the victim in your inventory. Do so, and move on to the gift shop. Now it tells you to distract the two guards that are talking outside the very dirty window. Throw a coin out the window in the right side of the gift shop, aiming for that rusty bulls-eye. Wait for them to be distracted and then sneak across the courtyard to the double doors to the theater.
[NOTE: There is a hidden TMP in the courtyard. After distracting the guards, stand behind the white pillar and wait till the guards have gone back. Now throw a coin at the other side. Wait for the guards to go and go to the rubbish heap. There is a small white cardboard box. Stand on it and TMP will appear on the pickup key. Take and holster it quickly before entering the theater - you may have to distract the guards again.This is most probably an easter egg, as the clip has 666 ammo.]
Kill the guard that's terrorizing the lawyer, and take his pistols. Climb up the lattice-work and jump across balconies. Choose either the SLP .40 or the Shotgun to kill the two crack-snorting gangsters in the next room. "Dispose" of them by dumping their bodies in the two containers in the room, and then grab the Kitchen Knife and hide in the closet. A chemist will now enter the room (he won't notice the blood stains). Step out of the closet and stab the chemist / throw the knife at him when he is standing over the table to take his clothes and Keycard. Drop his body over the balcony if you want to.
Proceed to the walkway with the keycard, and walk to the room where the green crate of baking soda is. Grab the ammunition for the SLP and place the gun in the crate. Go back out to the walkway and walk to the gangster who stops you to search you. If you still have the kitchen knife or TMP then he will very promptly make it known that no weapons are getting past him (except for the .40 caliber pistol jammed into a bag of baking soda). So give him the knife and continue onwards. Put the crate down and retrieve your pistol. Now hop down on top of the elevator and fiber wire the guard, taking his place and continuing to the edge of the drug factory.
Break the utility box and then sneak through the factory, headed towards the toilet. Grab the TMP machine pistol and grab the guy who's using one of the toilets for a human shield. Shoot the three gambling gangsters in the next room, but make sure you don't ditch your unfortunate shield quite yet. Make sure no gangsters from the factory itself run in to see what the commotion is, otherwise you're shield-less.
Killing "Swing King"
To kill Clarence, climb up the ladder in the room with the gangsters, and then grab the sniper rifle case and break it open to reveal the SVD rifle in it. Now snipe the 3 guards outside. Their locations are as follows: The guard on the Ferris wheel platform is to 47's right, another sniper is almost directly in front of 47 back on the building platform, and a third is down on the ground walking around the few little shops long closed. After killing them, replace the SVD in its case and leave it there, or take it with you. It really doesn't matter. Go out onto the balcony and climb down the drain pipe. You can take ammo for the SLP .40 from the dead gangster in the open on the ground, but head towards the office. Pick up the Poison syringe, and watch as the gangster flirts with the blonde secretary. After their exchange, she gets called away from the gangster. So push him over the railing, and poison her drink in the vintage Coke bottle. Hide in the closet and wait for her to sip the drink.
Just leave the room with the secretary dying and enter Clarence's office. After the exchange between them, kill Clarence however you'd like. Execute him with the pistol, grab the hammer off the desk on the left or the baseball bat of the wall on the right and take him out with that, or fiber wire / syringe him.
Leave the office through the window on the left of Clarence and grab the Bomb and detonator from the crate and continue to the last room, with Scoop, three gangsters, and Scoop's lady-friend. Plant the bomb by the rigging control for the lights, and then detonate it, killing the three gangsters (sometimes Scoop will be killed too if he reacts quickly enough). Kill Scoop, and kill his lady-friend too (she's a witness). If you want you can grab Scoop's Desert Eagle. Choose the weapons you want in the Hideout and keep them all in the ICA crate where you picked up the RU-AP mine. Leave through the door marked "Exit".