I am shocked, amazed, and a little saddened. No one has started a topic about these games. I have played all five, starting with the first one, but I lean towards Kain. So both Soul Reaver's I played half heartedly.
If you have never heard of them, how can I get you to play? STORYLINE!!!

Over the course of the five games the story line takes twist, turns and even rewrites itself. The characters are rich, with distinct personalities. (Supported by some of the best voice acting in any game)
Summary:
This is going to be hard. But just to give you an overview.
Blood Omen
We start with Kain a young nobleman, traveling alone. He is kicked out of a bar and then murdered. He is then raised by a Necromancer as a vampire to take revenge. In many games that would be the whole plot. In Legacy of Kain that is the first 15 minutes. Now Kain wants to reverse being a vampire. So he goes to the Pillars of Nosgoth to get some answers. The Pillars are decaying. Kain is sent on a quest to straighten out the pillars. Which involves killing the corrupted guardians. In the course of the game you met Malek, Vorador, and Moebuis. characters that make appearances in the other games as well. Kain also discovers he has been used and his murder was ordered. There is a major decision to make at the end of the game. And the rest of the games assume that you choose to let Nosgoth fall.
Soul Reaver
Kain has been busy. He has become a vampire ruler of Nosgoth. Using his nine Lieutenants. They all have been evolving and changing. His first lieutenant Raziel developes wings. Kain kills him. Raziel is raised again, a sort of un-undead afterlife. Raziel goes back for revenge. All of his brothers have evolved. Raziel ticked off and decides to wipe out the vampires that are left. He misses Kain and Turel.
Soul Reaver 2
Raziel is on a chase through time to catch Kain. As he travels through Nosgoth he starts to find out some very ugly truths about the history. And finds out that the Vampires are not the monsters they have been portrayed.
Blood Omen 2
to be fair this is the weakest of the series, but it is still a good game.
This takes place when Kain was still young. He was injured in a battle so badly it takes him years to recover and that is where the game begins. Now you find out that their is another race on Nosgoth, aliens known as the Hylden. This is a sort of a strange adventure, that doesn't seem to tie in to the rest of the games.
Definace
The last made, hopefully not the last one ever.
This time you get to play both Kain and Raziel. A lot of story line is tidied up. Except for how Vorador lost his head inthe first game, but was back in Blood Omen 2.
Other reasons to play.
*Vampires on Nosgoth are not whiners. Unlike other vampire games there is no half vampire trying to kill them all (the Vampires of Nosgoth have enough humans doing that).
*The style of gaming spans Legend of Zelda style, cyberpunk, and swords and sorcery.
*Kicking butt. Face it that's why you play. Kain is my favorite for that. In Definace especially. Any character that can bounce someone up and down on their sword then knock them into a spike, is fun to play.
*The Soul Reaver. That is just one awesome sword.
* In later games, the out takes. Watching the footage of the voice sessions is well worth playing hours of games. A good example (Not one of the funniest) Is when René Auberjonois is looking over his script. He asks what type of game it is, because there is a lot of lines. He is used to coming in a recording 20 takes of "Don't go through that door." "Don't go through THAT door." "Hey Asshole, Don't go through that door!"