Prey is one of the few games I’m anticipating this year.

It has something interesting to say on every front: a top-notch engine with advanced features, innovative design and gameplay, the best art that is possible to expect and first quality sounds and music (Jeremy Soule again). Along with many other smaller elements like dynamic elements in the environment (like spikes coming through the pavement), an innovative death system (spiritwalking) and perfectioned light and animations systems for the monsters.

I already commented the previews of the game a while ago. These days 1UP is giving the game a special week coverage and the articles have been rather interesting, confirming that my expectations and hopes were well put.

Today’s article gives more details on the work thay have put on the Doom 3 engine to add the new features that are deeply tied with the innovative game design behind the game. And this is also why I consider it so much interesting. It is trying to revolutionize the genre (FPS, in this case) by breaking up some of the basic patterns to introduce unpredictable elements. By developing specific technology to support their design ideas they can shape up the game to radically change its structure and principles. Their portal system mixed with the variable gravity system and the “wall walking”, promise to open up a whole new dimension for this genre.

So it goes right to the core of the gameplay, to untap a potential that remained hidden or underestimated till today. Demolishing the feeling “on rail” of the current FPS, that too often are limited to more or less pretty two-dimensional labyrinths. In this game all the principles and rules at the base of the genre are broken. The rooms can flip upside down, the monsters can walk on the ceiling and walls, and the portals destroy completely the limits of the perception of the space. Every game starts with a set of rules that the player quickly learns. Here the boundaries of what we have seen till today are broken. The design started from the beginning with the aim to push those limits.

We still have to see if the execution will match the ambition, but the design ideas and the technology behind are rock solid. The possibilities they opened are endless.

One of the original Prey engine’s novelties was a little invention called Portal Technology (PT). The premise was simple: Instead of stepping into an elevator, hitting the Up button, observing the onscreen action grind to a halt, and then waiting for the hard disk to load the next level, Prey teased a braided area system that essentially warped Euclidean geometry (the solid geometry that defines the three dimensional sort of space we live in) by allowing the existence of hierarchical levels within levels.

“Our portal system allows you to move fluidly from area to area, orientation to orientation,” says McArthur, adding that general objects in the world can pass through the portals as well and that the developmental obstacles were manifold. “Several elements in a game need to be dealt with to produce fully functional portals. First, we have to render the scene from the point of view of the destination portal, which is the kind of portal.” In Prey, however, that’s just the beginning. “The fun part of portals is the creation of impossible non-Euclidean spaces where you’re being torn away from the expected,” says McArthur, hinting at labyrinthine, Escher-like conglomerations. “As players of FPS games, we’re used to mapping out an environment in our heads and having these realistic 3D spaces. We’re not expecting spaces to overlap each other or lead back into each other. The most interesting use of portals occurs when you don’t realize there’s a portal at all, where you’re just experiencing an environment that your mind says isn’t quite right.”

According to McArthur, one of the biggest challenges involves getting motion through the portals to stay smooth while the orientations are changing radically. Likewise with weapon ballistics. “Having weapons fire through portals can be troublesome with ray-cast types [weapons fire with only one endpoint],” says McArthur. “Also [troublesome is] getting high-speed projectiles to play well with paper-thin surfaces. All of the weapons in the game are subject to the laws of physics, so shots over long distances will drop toward whatever the local gravity direction happens to be.” Fire into a portal that reorients gravity, in other words, and your bullets could be bending some serious curves.

This also raises the question of noise. Imagine getting sound to flow through a portal so that even though it may be emanating from an object a mile away, you can hear it through the portal as if it were right next to you. “We do that, too,” says McArthur. “The sound system was altered to allow not only audio flow through doorways, but also through portals.” Add AI navigation modeling to the mix–how AI peers through and navigates a portal–and you can see how Portal Technology has a trickle-down impact on every major system in the game.

Gravity and weight are, in fact, central to a variety of gameplay elements. “We can have gravity fields of any shape, strength, or direction, or in all directions as in the case of the local gravity field of a small planet,” says McArthur. “Of course, the projectiles will obey these fields of gravity, which may in some cases make them appear to go snaking through a maze of invisible forces.” These fields can change or be affected by the player as well (Ender’s Game, anyone?), and though the alien sphere in which the game takes place lacks traditional environmental conditions (e.g., weather effects like rain and thunder), the sphere is prone to electromagnetic storms that can produce tears in space and gravity sinks.

Couple gravity with juggling orientations and you get another of Prey’s curious gameplay variants: wall walking. “Wall walking is the ability to walk on marked surfaces within the game regardless of their orientation,” explains McArthur. “We use curved surfaces to great extent, allowing you to travel in directions that would normally require an elevator or ladder, as well as spaces you’d simply be moving through in another game. So instead of walking through a building, for example, you might be walking up its outside surfaces.” McArthur says this is intended to give players a different perspective on areas altogether by allowing vantages from any angle. “Prey’s wall walking and manipulation of gravity required that all our characters and players have the ability to exist at any arbitrary orientation,” continues McArthur. “The combinations of these factors required that the systems be very robust.”

There isn’t such thing as “enough hype” for this game.