The butterfly effect's been mentioned a few times in Until Dawn's PR, a cause and effect system that alters outcomes and options as you play. According to director Pete Samuels it creates hundreds of endings and thousands of possible ways to get there.
Until Dawn's teen horror movie homage resurfaced at this year's Gamescom after a long silence. In that time it's transformed from PS3 Move oddity to a sterner, Eli Roth-tinged horror game that's promising hardcore scares. It's a classic mix of teens trapped on a mountain, a ramshackle cabin and murderous mask wearing freak. How those familiar ingredients mix however is up to the player, and if developer Supermassive deliver on its promise it will create near endless potential. "Everyone can survive and everyone can die", explains creative director Will Byles.
The potential variation goes deeper than just a Heavy Rain-style, 'who's left at the end?' set up. The idea of a butterfly effect means that almost anything can have an impact on the story, and the route you take through it. "Somebody might choose something insignificant that they did halfway through [which] means they had a very different story to someone that didn't do it," explains Pete. If you want to pick out every possible variation the game throws up at every level he claims that the possible combinations reach "17 million million million... some stupid ridiculous number", but adds that that level of differentiation is, "clearly dishonest because that doesn’t define a unique story".
"You don’t simply get to the end of our game and chose the ending you prefer. All possible variations on your ending are determined and influenced from the outset"
Instead, the team is focusing on "hundreds of significant, noticeable variations on your ending" according to Pete. These will be reached via various branching paths involving conversations, decisions and deaths that he says create "thousands of different routes towards the end". Choice will apparently be shaping your story the whole time you play.
"You don’t simply get to the end of our game and chose the ending you prefer. All possible variations on your ending are determined and influenced from the outset. That’s the butterfly effect," explains Pete. "Whatever you do through the game is going to define, and carry on defining, how many of these endings are still available to you. Until obviously, when you get right to the end, it’s limited at that point as to what the outcomes can be".
These variations won't always be obvious, huge junction points either. "It can be quite a small action you take that causes the ripples," explains Pete. The ramifications of these decisions will be logical he claims: "It isn’t random. It’s not that you do this one thing and something else happens 50 yards away immediately on the mountain. There are connections between what you do and how that influences what other people think and what other people feel".
So rather than choosing door 'A' or door 'B', influential actions can be as basic as a conversation that "changes [a] character’s beliefs or perceptions of the situation [and] therefore makes them behave in a different way when you’re not controlling them". Although it can span right up to obvious major choices such as the one shown at a recent Gamescom demo where the player was forced to choose between killing themselves or another member of the party. "The immediate ramifications of that are fairly transparent," points out Pete, "but even in that one instance there are further big ripples and ramifications based on the choice that you make there that just aren’t apparent at the time that you make that call".
This level of variation and the fact that no character's survival is guaranteed means that the game's story has to be built with multiple combinations of characters in mind. The example I proposed to the pair was a fictional cut scene towards the end of the game with two survivors. I asked if, would that have to be shot with every possible combination of character to allow for every possible outcome? "That’s correct, yes," says Pete. "It’s genuinely a huge, huge undertaking," adds Will, highlighting previous claims that no one is going to see everything, possibly even after multiple playthroughs of what't purported to be a nine hour game.
One feature that will really underline all this is that you only get one save, says Pete: "Each time you make a significant choice we replace your save game". As someone with the worst willpower in the world for re-loading checkpoints until I get what I want, I actually love the idea of this: being forced to live with your decisions is something games rarely do. "You could certainly go back to the start of the game and start again if you wanted", says Pete, "but you can’t go back to the previous save until you’ve completed the story once".
It's going to be a controversial decision and one the team is aware could be painful. "One thing we have to guard against there are some of the frustrations where people might see something that they wanted to do, put it off doing it until later and then not get the chance to because they did something else. We’re conscious of that as a potentially frustrating mechanic for players, so we’ll build our design to accommodate that. In essence though, you go along a path, and just like life, once you’ve made your decision you can’t then make another one".
Until Dawn will be releasing on PS4 in '2015'.