Whether you play quiet as a mouse, or like to wreak havoc, you cannot avoid the occasional hacking mini-game. With so many icons it can get fairly confusing. We've put together this definitive hacking guide!
How To Hack in Deus Ex: Human Revolution:
Your goal is to reach the Registry (the white sphere) or the Diagnostic Subroutine, if a bridge connects to it, but this is the exception rather than the norm. In any case, to reach your goal, you need to capture nodes. You can only capture nodes that are connected by bridges to nodes you have already captured. Even then, the direction of the bridge also comes into play. If your node is connected to four others, and only one bridge leads out, you can capture only that node. Clicking on a node gives you the four options discussed above: Capture, Fortify, Stop and Nuke.
Rating and Attempts
The rating of a node determines how long it will take you to capture it, or for a trace to get past it. You can fortify a node only after capturing it, but it has the advantage of slowing down the trace when it tries to overcome a captures and fortified node. Each system you come by will have a certain number of attempts. If you disconnect for any reason (ran out of time, for example), you will lose he attempt. You can immediately try again until you run out of attempts. If you run out of attempts the system will go into lockout for 30 seconds.
Lockout and Alarms
A lockout is not an alarm, and it is important to understand this. A lockout simply means a 30 second ban from hacking that particular device. You can choose to load a quicksave game or just wait out the 30 seconds and try again. So you can hack a level 4 security device with 3 attempts 3 times before you are locked out for 30 seconds. After the 30 seconds, you will have 3 more attempts.
A system will trigger an alarm if the trace successfully captures your starting I/O node, never otherwise.
Take Your Time (Except in Some Situations)
The most important think when you start a hacking mini-game is to do absolutely nothing. Starting the mini-game has no consequence. You can stare at the network of nodes for an hour if you wanted without being at risk of getting traced. This is a deliberate design to allowing you to study the layout before you start. Look at all the nodes, determine the most optimal routes, look at which bridges allows traveling in which direction, and always check to see if the Diagnostic Subroutine itself can be captured. If it is, that should automatically be your top priority.
Your path will be determined by your play strategy. If you are a completionist, you will want to capture all Datastores before you capture the Registry (or the Diagnostic Subroutine), or you can beeline straight to the registry (or the Diagnostic Subroutine), which is normally significantly easier.
Using Nuke and Stop
If you capture all Datastores, you will end up with a very healthy supply of Nuke and Stop viruses (I finished the game with 80+ Nuke and 60+ Stop viruses). You should use Nuke only if you consistently fail at capturing a high-level node that is quite far from the intended target (Datastore, Registry or Diagnostic Subroutine). If you are relatively closer, even after triggering the trace you can attempt to capture the target nodes.
As mentioned in the Augmentations Guide section, you should prioritize investing in the “Stealth” tree. If you have it fully upgraded, you will almost never need to use Nuke, except nodes with a security rating of 4 or 5.
The stop virus only comes into play if you have triggered a trace. Use this to stop the trace for five full seconds as you scramble to complete the mini-game. Don’t waste this virus if you think you will lose any way. Remember you can simply disconnect and lose an attempt, without ever triggering an alarm. Use Stop only if you feel that you will be able to capture your target nodes in those five seconds.
Capturing Multiple Nodes
You can capture as many nodes as you are able to. If the nodes you have captured so far allow you to capture 6 nodes, you can capture all 6 simultaneously if you want to. This is completely situational and especially comes into play when you are trying to capture high-level nodes.
For example, if you aim to reach a Datastore which is protected by a level 4 directory node, and a registry protected by a level 4 directory node, I would capture both directory nodes simultaneously as it is highly likely that I will be detected and a trace will begin. Both nodes will capture simultaneously, and a trace will likely start. I can then capture the Datastore first, and time my Registry capture such that the registry is captured a split second after the datastore is captured.
When to Fortify
Fortify is tricky, but follow two fundamental, and one flimsy rule while fortifying.
First Fundamental Rule: always fortify a node with a level 0 rating as you can fortify it without any threat of detection. This is especially true if you have invested Praxis points into Fortify.
First Flimsy Rule: Depending on how complex the network is, it may be a good idea to fortify all level 1 nodes, especially if the path to the Registry is excruciatingly long. This is highly situational and not needed, and there is no way to dictate when exactly you should do this, but as you get better at the hacking mini-game, this strategy will make sense.
Second Fundamental Rule: When a trace is triggered, regardless of rating, first start a capture of all nodes you have access to, and second, fortify all nodes you have already captured. In the remaining time, always try to squeeze in a Fortify action when waiting for nodes to be captured, because each fortified node will add precious seconds to the timer. Again, if you have invested Praxis points into Fortify, this is all the more critical.
Automatic Unlocking Device
There are a few level 5 security devices in the game. In order to save on Praxis points, some players upgrade Hacking: Capture to only 4/5, and simply use the Automatic Unlocking Device. The AUD captures any device instantly and allows you to access whatever it was protecting. Since you have completely bypassed the hacking mini-game, all related rewards (Datastores and bonus XP) will also be lost.