Helpful Preparations
- ECM with pager delay and door opening (The more pager delay you have, the better)
- As low detection risk as possible
- Dominator & Smooth talker (useful if caught before grabbing the server a lot to save the situation)
- Cameras
- A lot of patience
The achievement requires no alarms and no computer. You are allowed to be detected as long as no alarm goes off before in the debriefing screen.
Completion
Part 1: Security Boxes
You're looking for small white boxes on the walls. You'll want to avoid guards and breaking cameras at all costs as there is no way you can take out all of the guards on the level. There are at least 7 guards every time and they seem to be replaced with new ones as you kill them off.
First off, you'll want to check the cameras to see if you can find any of the security boxes. If possible, have a friend sit on the cameras checking for guards that are coming your way at any given time. Check the outside walls and the lobby first, because they are the easiest possible locations for the boxes.
Once you have located a box, you can open it, cut the wire and close it. The guards will notice an open box and call an alarm.
NOTE: You must be standing in order to cut the wire.
This part of the mission is random. There are three security boxes and you need to cut two wires. One of the three boxes triggers the alarm. If an alarm goes off, restart the mission and try again. It can take quite a few attempts to get the correct boxes.
Part 2: Server room
Once you have the wires cut, the alarm for the server room door is disabled. Find the server room. The safest way to find it is to check the cameras for the door. There are four locations where it can be:
- Next to the back door
- Above the lobby, a bit on the right
- At the back wall next to the room full of computers
- At the back wall next to the glass room (meeting room)
Only one should go in and he should have his ECM upgraded to open doors. Sneak to the server room door without being seen and pick the lock when there are no guards nearby. Open the second door with the ECM and grab the server. Guards will notice the second door open and will come check it out. Sneak out as fast as possible and finish the mission.
If you get caught while carrying the server and you have a player with pager-delaying ECMs, have him chain his ECMs one after another as you run out killing all the guards you see on your way. The alarm will not go off until the ECMs run out, but the ECM MUST HAVE PAGER DELAY. If your ECM is not upgraded with that, answer the pager of the guard that caught you and then run and hope for the best.
You have to destroy the rail windows, the windows form the store and the small ones that are above, the windows from the third floor (the interior windows), the ceiling windows and even the windows from the gym and from the closed shops.
You can even break the windows from the car that is displayed in the car shop but I have no source if that counts towards the goal.
Best Answer
The mission is bugged and will not properly display how many snipers you've killed. I've done this mission before and you just have to keep a mental check of how many snipers you've killed. Once you've killed 10, you'll get the achievement and the relevant weapon mods.