A House of Cards
It seems like the game makers decided to throw a couple of easy ones in for us. This one is also a cinch as long as you bring the silenced W2000 sniper rifle, which can be useful to bring. Although this level has a lot of armed personnel and can easily turn into a bloodbath if you go loud, it's still easy if the methods are right. The ICA crate in this mission for some reason has some goodies for you: an extra RU-AP mine, a TMP, and some sniper rifle ammunition (not W2000 ammo, unfortunately).
Infiltrating the Hotel
First thing you should do is go to the front desk and talk to the receptionist. She'll give you a keycard to Room 701. Your keycard will only allow you to take the elevators to the 7th floor and it'll only work on Room 701. Not to worry; there's a solution to this. You'll find out in due time. One thing you should know: you cannot use the elevator until you get your keycard and the police will stop you if you arrive at the wrong floor.
There are some waiters in 7th and 8th floor, you can knock them out in the staff room (usually there is a fridge to dispose their bodies). Then you can take their clothes as a disguise and the 7th/8th floor keycard - you can now enter every room on the 7th and 8th floors. This will also give you access to the elevators and not being alerted by the guards as well. Your targets will take a while to show up (though one is already in the casino), so you will have some time to prepare.
When you are walking through the casino, stick to the hallways on the right since there are CCTV cameras in the corners of the room with slot machines. If you get spotted, you can steal the tape in the guard office to the left in the lobby to avoid "caught on camera", which will result in rating and score penalty.
Tariq Abdul Lateef (Scientist)
Take the keycard and go up to the elevators. Facing them, you'll want to take the one on the left. You won't actually go anywhere though. Just call it, step in, wait for the doors to close and then jump up the elevator hatch. While in the hatch, the trip can be somewhat boring, so be patient. Keep an eye on the map and the information notices. Eventually the scientist, Tariq Abdul Lateef, will arrive outside. Take out your fiber wire and watch him on the map: he will cross the lobby and eventually, and coincidentally, enter the elevator you are camping on top of. Once the doors close, strangle him (default E key on PC). 47 will pull the body up onto the top of the elevator, so don't worry about anybody finding him. Take his keycard and jump down before the elevator reaches the floor. If it does, and you're still on the top, just wait for the doors to close. Grab the briefcase the scientist was holding and take the elevator back down to the lobby. It is recommended to keep the briefcase on the top of the elevator, for security reasons, because you cannot take 2 briefcases at once, you can put the W2000 rifle in the ICA crate, and get the diamond briefcase. If the briefcase is taken by police officers, they will be kept in staff quarters. Be careful about the timing while you are attempting to strangle Lateef, if the guards see you do this (this will happen if you don't wait for the elevator's door to be fully closed) the mission will be ruined badly. (at least getting the SA rating is not possible)
Lateef's room is 803, be careful though, several bodyguards will be deployed there.
Another method in killing the Scientist, if you want more of a challenge: After taking care of Hendrik Schmutz, take his DNA research briefcase and his disguise and plant an RU-AP mine in said briefcase. Proceed to the private area behind the bar where you are to meet the Sheikh while pretending to be Schmutz. The Scientist will arrive with the Diamonds Briefcase and take the rigged DNA research briefcase with him. There is no need to worry about detonating the mine manually. That will happen when the Scientist returns to his room to inspect the DNA research briefcase--it will blow up in his face a split second after he opens it in the cutscene. Since the Scientist will not be able to call the Sheikh to confirm the DNA research is genuine, you will need to quietly and quickly dispose of the Sheikh as well before you can leave, remember you can hide a gun in the DNA briefcase as well.
Another method that will surely get you SA: Leave the scientist alone at first. After taking care of Schmutz, take the DNA briefcase to the sheikh. A guard will take it away, while leaving the payment briefcase. Some time later, the sheikh will go outside for a phone call. Follow the sheikh, but double back as you leave the casino. A guard will be angrily telling you not to go. Wait for the guard to holster his gun and turn around before getting out through the doors. Go up the staircase, into the area outside and fiber wire the sheikh. Go back and collect the payment briefcase as you leave. Now go to the 7th floor to the balcony on the other side of the elevators. Climb up the trellis, making sure the waiter doesn't see you. Walk along the ledge to the open window on the 8th floor (your left side when climbing). Make sure the patrolling cop is nowhere in sight before you climb in. Now activate the fire alarm closest to the scientist's room and run into the room after the last guard goes out. Hide in a closet in the bedroom. Some time later, the scientist will return. Sneak up behind him and fiber wire him. If he turns, knock him out and use poison syringe. Take his keycard and walk out of the room in style through the bathroom : there is a guard inside the other room. The guards outside will be suspicious, but they won't shoot you. Now get back your suit and payment briefcase and exit with an SA rating.
Similar deal to before. Once in the lobby, take the opposite elevator and jump up into the hatch like before. Wait there for a while (watch the target on the map in the casino, generally after you deal with Lateef using elevator hatch method then you can go and wait). Eventually, Hendrik Schmutz will enter the elevator (to the right). Same as before, once the doors close strangle him using the Action key so that his body stays on top of the elevator. Take his keycard too and his clothes if you fancy wearing some jeans for once and then take the elevator to the eighth floor. He will get to 7th floor after his dealer arrives, so you know when to prepare. It's possible to make his death look like an accident by knocking him out in his room or in the hallway, dragging him into the room, activating the fire alarm in the hallway, dragging Schmutz to the balcony railing and throwing him over it. Another, perhaps a bit more stressful way is to go to the bathroom on the righthand side of the casino. Wait in the corner behind the stalls, and when Schmutz arrives, nudge to the man who always is in the bathroom flexing. Then, you can silently take out Schmutz any way you choose.
Remember to get your suit back if you are playing on higher difficulty, you will get more money for "Suit retrieval".
You have to ask the blonde girl at the bar about him and she will give you a letter telling in which room he is.
Mohammad Bin Faisel Al-Khalifa
This guy involves more effort but it's not too difficult. Make sure you have the sniper briefcase, leaving the payment briefcase that the scientist had on top of one of the elevators. Remember which elevator so you can save time later. Take the sniper briefcase and head up to the eighth floor. When you come out of the elevator, go right. There'll be a corridor to your left, which you should take. Go right to the end and then right. Follow that corridor around and you'll find some guards standing outside a room. Instead of fighting your way in, go back around the corner and find a fire alarm out of sight. Pull it and wait for the guards to run past, following procedure and heading for the elevator. Once the three guards are gone (there's another one idle inside the room) use the keycard you took from the scientist to enter.
Once inside, you should wait in the bedroom for the fire alarm to end, and the guard to return to his post by the window. It makes this a lot easier if you wait for him to return and then take him out, otherwise he could see you on the balcony doing your business. Either way, if you wait for him or hurry before they return, unpack your sniper. Redial the phone on the table in the bedroom and go out to the balcony. Make sure you sneak so that 47 is partially hidden, as sometimes a staff member who is smoking on a balcony ahead will sometimes see you otherwise. If you look directly down, you'll see a little rooftop area with double doors. If you read some of the intel, it tells you that there is no cellphone reception inside and so to answer a call, someone must go outside. Keep an eye on the double doors and wait for the Sheikh (Al-Khalifa) to exit through these double doors. Snipe him quickly and you'll have killed all your targets.
Note: Once he is dead, the area will in full alert. So long as you are not spotted, you should be fine.
Another way to kill the Sheikh is by using poison. Though you might be caught in the process, it is recommended to save before entering the private area of the Sheikh in case anything goes wrong. After killing Hendrik [by elevator strangling method] Get Hendrik's clothes (optional) and the keycard to his room, and gun if necessary. Then head up to the seventh floor. Go to Hendrik's room [Room 707] and take the DNA briefcase. Do not place anything in the briefcase. Go to your own room [Room 701] and then store all your weapons in the ICA crate. Do not even take melee weapons. You can keep your Fiber Wire, Syringe Sedative, Syringe Poison, RU-AP Mine and Detonator with you as they do not get detected by the security devices. Go down to the lobby, then casino and to the north east where the sheikh is.Let bodyguards search you and then enter private area. Turn left and talk to the Sheikh. After the cutscene, use the poison to kill him (best to face away whilst you get the poison out). Leave the body where it is.
Another alternate (and much less discreet) method to kill the Sheikh. Take out the other two targets in the elevators by using the fiber wire method. Then dress up as a hotel guard and return to the Hotel entrance. It is safe to have your SLP.40 drawn while wearing the guard uniform. All this must be done before the Sheikh's car arrives. The moment the Sheikh's car arrives, walk up to it. A cut scene will be shown above as the Sheikh is getting out of the car. If you are close enough you can see yourself as well. As soon as the Sheikh is out of the car, shoot him point blank in the head with your SLP.40--you will see yourself killing the Sheikh in the cutscene as well. Then run like hell and make your way to the escape point! No Silent Assassin rating here for obvious reason but still a fun method to use.
All Three (No Silent Assassin)
An alternate way to kill all three is to go to the 7th floor, enter 47's room and cross the balconies to enter Schmutz's room (707). In here is his DNA Sample Briefcase. You can simply place an RU-AP mine in here and wait for him to take it to the meeting. Once he is there, you simply detonate the mine and you can leave. You won't be able to recover the payment, though. This is a very stylish (and easy) approach, but requires extreme patience, as you must wait for all three targets to arrive at the meeting. It also keeps you from earning Silent Assassin, unless you manage to discreetly remove all guards in the vicinity of the explosion.
You can also strangle the scientist in the elevator, take the payment briefcase, go to room 707, plan the bomb in DNA sample briefcase and wait for Schmutz-Al Kalifa meeting to blow the bomb, then escape with the payment
Presumably, case-bombing the Payment Briefcase would also work, but is slightly more difficult. 47 can reach Schmutz's room without issue (they stay on the same floor and Schmutz is out of the room for most of the mission) but Lateef stays on the 8th floor, requiring stealthy climbing or a keycard, and Lateef tends to stay in his room with a group of armed guards.
Recover the Payment (optional)
The scientist carries a payment briefcase. After killing him, retrieve it and finish the level with it to get a bonus. If you do the "elevator strangle" you can quickly come down, take the briefcase and back into hiding. To not have to pay for recovering custom weapons like your WA2000 rifle, you can go into your room on the 7th floor, unfold your rifle and place it in the ICA box. That way you can receive the bonus for getting the payment briefcase without being annoyed by letting your sniper rifle behind you. If you had put the diamonds briefcase on the top of the elevator on which Abdul Lateef was killed, retrieve the case, and continue to escape
To escape, go back to the lobby and go downstairs into the casino. To the left is an exit. Go through the doors and outside to the waiting car.