Like any other game, the first mission is usually the tutorial stage. Take note of the basics here since you’ll use them for the entire remainder of the game. For the first part, follow the instructions and climb over the ledges, jump over the gap, the climb the ladder.
In this part, you’ll need to move behind cover and sneak behind the guard. Sneaking will maintain your stealth and also protect you from bullets in a firefight. For now, you have to knock out the guard by melee attacking him, preferably from behind.
Next, equip your stun gun and use it to shoot the guard below. Once done, jump down and take out the next guard as well. At this point, you can already use the NetHack view by pressing R3. You need to go upstairs but don’t forget to grab the money bag inside the open container van beside the stairs.
Follow the mission marker and you’ll find the locked door. To unlock it, you have to find the Closed Circuit Terminal (we’ll call them CCT for this walkthrough). To know its location, you need to follow the data flow. You can track it easily using the NetHack view. For this instance, it’s located above so go behind the entry point and use the ledge there to reach the roof. Simply interact with it to successfully disable the CCT. Once done, you’ll be able to get in.