Darkwatch tells the tale of Jericho Cross, your typical "black hat" outlaw who accidentally unleashes a powerful vampire lord during a botched train heist. Jericho's folly eventually leads him into the service of the Darkwatch, the secret society whose job is to protect the world from supernatural forces and the people who captured the vampire lord in the first place. In addition, Jericho is also turned into a vampire himself, giving him a completely new purpose in life; fight the forces of evil, or succumb to his curse.
Jericho's choices make up the backbone of what would otherwise be your typical shooter. At various points in the game you are asked to make a choice during "Judgement Events". For example, you can help a sick woman by sucking the tainted blood from her veins or end her pitiful life and nab a quick health boost. The choices you'll be forced to make are cut and dry with no gray area between, which can make the system feel tacked on at times. Unlike other games with "moral choices", there's no persistent counter that judges all of your in-game actions. Instead, it is all about what you choose to do during predetermined events. The choices you make determine the powers you'll earn.
The system feels very similar to the Jedi Knight series and gives you a choice of good and bad powers. Whether good or bad, most powers have the same effect, though some of the higher-tiered powers are pretty unique in what they do and actually make it really hard to decide which you'd rather have, which ends up speaking well for the game's replay value. It's possible to balance between good and evil early on in the game, but there comes a time where you need to choose one path or the other.
A 16-player online component sets the Xbox version apart from the PS2 version -- so if you're having a hard time deciding between the two versions be sure to factor this in. Online, Darkwatch offers the traditional FPS multiplayer modes like Deathmatch and Capture the Flag, as well as something called Soul Hunter. From the few games I was able to play online, Darkwatch is a blast. Unfortunately, Mother Nature decided to drop the mother of all storms in my backyard, so I wasn't able to spend as much time online as I would have liked.