Tower of Vampires takes place on a distant planet that is entirely forested with dark, hundred-foot-tall pine trees. At one point on the planet, for unknown reasons, is an enormous, menacing skyscraper of black and green glass.
An expedition of human investigators and settlers came here over the last decade, but now everything has gone wrong and they need to get off the planet as soon as possible. You are the leader of the special forces team who have come to rescue them. Unfortunately, the emergency ship you need to get the refugees onto is on top of the tower, and the tower is filled with vampires.
Your task is to clear each floor of the tower of vampires in turn and move all the refugees up from the floor below, until you eventually reach salvation. (To make this even harder, the vampires sometimes turn invisible and can shoot lasers at you.) As each floor is cleared, you score points for the number of vampires killed and the number of settlers still alive. You may also gain points from your characteristics, which I will explain in more detail.
As leader of the team, you have a characteristics sheet, and each storey cleared gives you another characteristic to add to the sheet. These characteristics come in three flavours: Moral, Physical and Tactical. For example, a Moral characteristic might be "Never abandons the body of a fallen teammate" and a Physical one might be "High endurance". As the tower has many floors, your characteristics sheet can grow very long, but only the top five entries are scored.
This means that at the end of each level, the player scores points for kills, lives preserved, and for the characteristics they have lived up to. They then receive a random extra characteristic from the master list and have the chance to rearrange their sheet, in effect setting their own goal for the next level of play. You can set challenges for yourself, or tailor the game to your own playstyle: for example, as David suggested, a cautious and methodical player probably wouldn't choose "Fights at full speed", but might pick "Never gets outflanked."
The settlers themselves add to your options. They are a motley bunch with a wide set of skills that could be useful, but perhaps a group of civilians is less reliable than your special forces team. Are you a commander who's "Open to unexpected solutions", or is it your priority to "Always defend your charges"?
This dream began with Lestat, Marius and Armand from the Vampire Chronicles exploring the tower and planet, but then turned into me and dream-David designing this game, complete with pages of handwritten notes, sketches and clay models of character designs. It was a good dream.