For a game closeted in so much mystery and intrigue, Quantic Dream has been surprisingly forthcoming about how Heavy Rain works and what it's about. We know that it sees four playable characters - FBI profiler Norman Jayden, private detective Scott Shelby, architect Ethan Mars and journalist Madison Paige - on the trail of The Origami Killer. We know that Ethan's son, Shaun, is kidnapped part way through the game and that, according to the Killer's MO, the player has four days to save him before he turns up drowned on a stretch of wasteland.
But it's still hard to predict exactly how the French developer will proceed, not least because its games - notably Fahrenheit/Indigo Prophecy - tend to encourage experimentation and present alternative outcomes based on your decisions, but mostly because each section of Heavy Rain that we get to play evades easy classification. Were you to show us the four levels that we've seen so far without the on-screen prompts for input that help guide the player's behaviour, you could probably convince us we were seeing four different but technologically similar games.
The Eurogamer Expo demo highlights the difference by showcasing a pair of scenarios. The first we've already covered in depth - it's Norman Jayden's run-in with Mad Jack. The other was at gamescom in August, but we spoke at greater length about Ethan Mars's night in with his son, so it bears more consideration. It sees Scott Shelby visiting a convenience store to question its owner, Hassan, whose son Reza was one of the Origami Killer's earlier victims.
Shelby is another of Quantic Dream's unlikely heroes - a portly forty or fifty-something private detective with a mild, avuncular manner - and Heavy Rain's unusual conversation system invites you to gently quiz Hassan by selecting from interrogation angles that literally swirl around Shelby's head. As the owner refuses to speak about his son, one can decide to sympathise, reveal that Ethan's son is in imminent danger, press forward less elegantly or even leave the store. Across a few playthroughs it becomes clear that there is one outcome - Shelby gets nothing out of the man, but before he can leave he asks if he sells asthma inhalers, and retires to the back of the store to find one.
Once you get to the back of the shop and locate the inhaler, the door jangles and a restless young man enters. He paces around before Hassan inquires whether he is after anything specific. He is - the contents of the cash register. Just as Hassan stubbornly refused to help you with your inquiries, however, so he proves reluctant to fork over his takings, even as the antsy robber waves a gun in his face.
Shelby, meanwhile, creeps around the aisles at your behest. Heavy Rain's movement controls are less obvious in promotional videos that mainly focus on one path of action through a scene, and inevitably stress the on-screen interaction prompts instead, but you're in control throughout, using the left analogue stick to turn Shelby's head and holding the R2 button to move him forward.
As you creep, prompts allow you to reach for items on the shelves - a glass bottle, for instance, and a cereal box that starts to tumble as you brush past. Whether you can avoid creating the ruckus that attracts the thief's attention, I don't know - I didn't manage it in four attempts - but it's an interesting possibility. Shelby appears to be unarmed.
He's not a bad talker though, as he demonstrates when the robber confronts him and the speech prompts start swirling again, this time bobbing up and down in nervous agitation. Shelby can reason with the robber, and eventually get into an altercation and subdue him with a few well-timed button responses. He can even goad him into taking a shot by refusing to put his hands up.
The camerawork here - as with the other demos - utilises split-screen techniques and builds suspense by refusing to answer urgent questions until it's ready: the bullet grazes Shelby's shoulder, but you won't be shown this until the robber has panicked and fled the store, leaving you to suspect you've failed. Quantic Dream's David Cage has previously said that there will be no "game over" in Heavy Rain, but it takes some believing, and we still wouldn't put it past him to let one of the playable characters die in a situation like this.
Whether Shelby takes the robber out or takes a bullet from him, the scene concludes with the shop owner thanking him and sharing a detail about the Origami Killer. As with the earlier conversation that sent Shelby to the back of the store, there's one way for this to end, and by replaying the scene you expose the heavy hand of the machinery driving you there. Then again, you would be unlikely to replay the scene this way in normal gameplay, and it stresses the ease with which the developer suggests deviation without actually having to offer it. Other scenes will certainly allow for fuller deviation - this one happens not to, but you wouldn't know it. It's rather elegant, and being able to identify the seams by going over a scene a few times actually enhances your appreciation of how effortlessly they're concealed.
If you get a chance to try the demo more than once at the Expo this week, then, it's well worth doing so. Sony may be just as excited about shooting monsters in the face in post-apocalyptic American cities as the next publisher, but it's hard not to admire the company's faith in developers like Quantic Dream when you witness their work first-hand. As Sony's Shuhei Yoshida pointed out when we raised the subject of Heavy Rain's commercial prospects a few months ago, "sometimes the most creative products give the biggest financial success". Whether or not it turns out to be the case for Quantic Dream's latest, that enduring optimism is a feather in the PlayStation's cap.
Heavy Rain is due out exclusively for PlayStation 3 in 2010.