Nosferatu tries to do something different, and it does very well, even with some bugs and mistakes.
You start the game at the castle's courtyard, and from there your can access all the three areas that forms the huge structure. But Nosferatu isn't a non-linear game as it may sounds, since most places are locked and you must find a key or a specific object to proceed. But there're many rooms that you can go without a particular order, and this will give you a good sense of freedom.
Also, you'll notice that Nosferatu features an intriguing randomization system, which is very good considering this game doesn't have a multiplayer mode. Almost everything is randomized, such as position of enemies and family members, items found in chests, and type of monsters you may face. That adds a good replay value to this game, although the random system could have been much better. For instance, if you quick save while standing in an area where you killed a monster, and then you load the game you may be attacked from behind, even if that place were empty before saving the progress. Also, random monsters are re-spawned every time, no matter if it's a place that you just visited or not.
The enemies you'll battle against in Nosferatu are all very well done, especially the vampires, the spooky bloodsucking undeads that rise from coffins. There are also ghouls, shadows, demons and so, each one with a particular behavior. And when you're gonna fight to one of them, a "jump" music starts playing and you'll know that something is wrong with that dark corner.
The sound in Nosferatu plays an important role, especially to build the frighting atmosphere. Most of the monsters squeal angry screams during the battles, which can be scary if you set your sound high enough. The graphics aren't bad, and the grainy textures will give a "nightmare look" while you venture deeper into the Malachi's castle.
Idol FX developers tried to stay away from the generic weapons of most of the First-Person Shooters, and by doing so Nosferatu will surprise you with the Crucifix, the Ancient Chalice and the Wooden Stakes, all of them useful. The Crucifix, for example, can bless the water to fill up the Chalice; while the stakes can be used as torches or even effective weapons against certain types of enemies. But there're common weapons too, like the revolver, the musket and the sword.
Rescuing your relatives is probably one of the most interesting concepts in Nosferatu. All of them are located in one of the three areas in the castle, accessed through the courtyard. But their positions aren't fixed, since most of them are located in random rooms, and if you decide to load a saved game, almost everything will change again. Anyway, it isn't hard to find your relatives, and when you meet one of them, he/she will give you some information and ask you to scout him/her to the courtyard, where is located a safe place, like a sanctuary, which the rescued family members stay. After bringing someone to the sanctuary, you'll receive a particular item, usually very useful against the demons in Malachi's castle.
The default difficult setting isn't too punishing, but it's enough to make the boss battles challenging sometimes. After defeating some of the though guys, there is an interesting thing, which I'll not spoiler here, that you must do to end the demon for once and for all. Also, I noticed that Idol FX decided to put two possible finals, both with cutscenes: one if you're victorious, and another one if you fall in the wrong hands, obviously shown when you're defeated. Even been a simple idea, I found that interesting.
The problem with Nosferatu is that every good concept present in this game is haunted by bugs or mistakes. First of all, rescuing the relatives can be a pain, since they stop following you when you load the progress, start fighting, or even when you touch them. So you need to approach the guy and tell him to follow you one more time. Also, most of your weapons must be reloaded, but you can do so even if the clip is full. Doing that repeatedly will suddenly empty all your extra ammo. I noticed too that some random items cannot be picked up, with any apparent reason. Another annoying bug is the "invisible" opponents, an issue that seems to be triggered especially in the final area of the castle. There're some other bugs, but I think the main problem is that you can experience a crash after a certain cutscene is shown, which happens when you're in the last area of the castle.
There are also some mistakes in Nosferatu, although I'll not list all of them here. There is only one I found really annoying: the clock. You must always run against the time, since your relatives are scheduled to be sacrificed at a specific hour. When seven of your relatives are dead, Malachi becomes immortal, and the game is over. In my point of view, a horror game must be played without any hurry, otherwise the suspense will be break and the most important aspect of the game is gone. Additionally, since you're always trying to do things fast, the game will finish as sooner as you can imagine.
I would easily rate Nosferatu as 9.0 or even 9.5, but the problems present in it made me lower the score to 8.0, and that's only because this game is so intriguing and ambitious that gave it a lot of credit. If you can overlook its issues, then you'll find Nosferatu a worth playing game.