Going off-topic, you might consider forking out a little bit of money and trying Vampire the Masquerade - Bloodlines. It's only about a year old and is selling for really silly prices (£2.95 on amazon.co.uk).

It's an RPG, rather than a shooter really, but uses the Half-Life 2 engine and if you want your vampire can shoot with a decent variety of guns (from a .38 special or shotgun to a Steyr Aug assault rifle or flamethrower).

The best thing about the game, though, is the dialogue, characters and quirky quests. (Early on there's a standout mission through a haunted house.)

Apologises for wasting your time if you've played it, already.