A prolific hacker has gone missing and his system, rigged with a dead mans switch, has contacted you in order to find out what has happened to him. You must join hacker groups, perform jobs to show your skills and improve your ranking so that you may acquire the information you need, or the tools to find it.
Hacknet is effectively a puzzle game, with hints of adventure games thrown in there as well. You will have an objective that most of the time boils down to gaining access to a system, after that you may have to copy, move, or delete files, but getting in is the bulk of the problem. You have a program that can crack passwords, but after the first couple of computers you hack you will have to open a number of ports on the target machine in order to successfully run it. So you steal an SSH port opening utility, type 'SSHcrack 22', telling it to open port 22, wait for it to complete and then run the cracker. Open sesame, you're in! More advanced networks need more ports to be open before you can access them, which require different tools that you can find or be given from whoever is issuing your contracts.
Running the different tools on your computer require memory be available, so if you need to open four ports you won't be able to run all of those programs at once. Some systems may start tracing you if you attempt any funny business, so getting in as quickly as possible is ideal. You may also store notes, someone's login credentials, an IP address, the name of the target file and so on. But these also take up RAM on your machine. While not a huge deal it is a slight annoyance when you're trying to remember some specific information but can't spare the memory space because you need to hack in as quickly as possible, and those notes are the difference between running three programs at once or two.
The main interface is a terminal, a command line prompt in which you can type commands, most, aside from the created hacking programs, will be familiar to unix users. To show the contents of the current directory type 'ls', to change to another, type 'cd ' then the folder name etc. There is also tab completion for commands and filenames. This all felt great to me, as I've used these sort of things for years. If someone had never used a command line interface before, it wouldn't take long to learn as there are few commands you need. You can even click around the file structure with the mouse if you so choose, although that would lose the magic a bit in my opinion.
Every computer you connect to, or find connected to computers you have broken into, appears on a network map at the bottom of the screen. Mousing over a node on the map will show its name and IP address, and clicking will connect you to it. This starts out fine but by the end of the game it became so dense with icons it could take minutes to find a specific machine if I hadn't had to use it that much. A searchable list, or even just a text list of system names would have gone a long way here.
Missions are fairly standard for a hacking themed game. Steal or delete files, edit database records, find information about people from message logs, but there are some more interesting contracts that turn up. Without giving everything away, at some point you are asked to hack into somebodys pacemaker. This involves hunting down the patient in hospital records, the manufacturer of the pacemaker, the company they use for the firmware, and finding a way to load specific firmware to the pacemaker remotely.
Hunting down information that you need in order to progress is fun, reading emails between employees who forgot their passwords or addresses of machines in order to find the next machine to crack. There are a lot of files sitting around in Hacknet, many of which have a gameplay purpose but also many just for flavour. If you know of bash.org you'll see a lot of familiar quotes strewn about.
It is almost impossible to bring up hacking games without mentioning Uplink, a much beloved game that became the defacto hacking game. Hacknet definitely scratches some of the same itches that Uplink did, the feeling of pressure as a trace closes in and you just need a few more seconds to delete these logs so nobody knows you were here.. But where they differ is Uplink felt more like a sandbox to play in. You would earn money from your contracts, upgrade your computer or software so you could go after bigger targets. In Hacknet all you earn from completing missions is progressing the story. That's not to say it isn't rewarding, but it is less open and you are on a much more defined and linear path.
Hacknet is a solid hacking game, leading you through a cool story. It's not your story however, and once the contracts dry up and the story is done, there isn't a lot of fun to be had when you can access every computer on the map with ease.