When the screen cleared, it showed a first-person view of a suspended computer monitor, surrounded by a clinical white environment. If you study the Project Assassins teaser trailer from last year, you'll see that the footage quite clearly pans through a clinical, white, environment - like a hospital.
Internet whispers suggest that the main character is actually a Twelve Monkeys-esque hero detained in a mental institute, who believes himself to be a warrior from - you guessed it - 12th century Jerusalem. The medieval action is really just you playing through this character's memories, as he relives them from his hospital bed, far in the future.
This speculation would explain why you don't have a traditional health bar. Our Ubisoft guide pointed out what Ubi calls a 'confidence' meter, which drains as you are hurt or discovered, but the developer is unwilling to reveal why it is important.
In the light of the storyline rumours, though, it would appear that the bar reflects the confidence the main character has in his memories. The stronger his memory, the stronger and more effective the 12th century assassin will be.
But while the game's plot is in doubt, what we're sure of is that the game wasn't running on an Xbox 360 at last week's E3 - despite what you may have heard elsewhere. Rather confusingly, the demo we saw was running on a PC but using a PS3 pad.
Obviously Ubisoft is keen to keep Assassin's Creed and its plot secrets a mystery, which would explain why it made no mention of this intriguing game's past appearances. But we'll keep digging away for info, and we'll be right back as soon as anything turns up.