These articles have been pretty fun so far, it's a chance for me to ramble about subjects that are near and dear to me. They aren't meant to be some insightful look into the inner workings of the game industry, since things are often subjective and based on your own views. In this article I'm going to be talking about something that is very important when you're looking to break the boundaries of certain established game worlds.


That's right, whilst you can have all the joy of building the perfect game environment for players to swan around in; you know that there are a large percentage of gamers that really just want to blow the living hell out of your carefully crafted paradise. I've stalked many message boards in the past and seen tonnes of 'what if' questions that have been focussed towards games like GTA IV and the like, what if we could decimate the city and blow up key structures!

This leads to several problems.

• If you define the whole area as destructible, including the terrain, what's going to be left of your game world when the player is finished?
• Do you make parts of the terrain immune to the damaging effects of explosives and high powered weapons?
• Will your system have any effect on the game's frame rate?

This is the largest quandary that game designers tend to face; I've faced it myself in the various jobs I've been involved in. When is enough, truly enough?

Volition crossed this bridge with the first Red Faction game and Geo Mod, the terrain/building destruction engine that powered it. Red Faction was the first game to truly take destruction in a game level/environment to the next dimension. However it presented several unique problems for the game's designers, the aforementioned destruction issue was the biggest one.

Volition had to choose between making it possible to level the whole playing field, thus removing any kind of challenge and making their key set pieces redundant or breaking the suspension of disbelief and making certain elements of the game, terrain included indestructible so that the player couldn't simply just blow everything to kingdom come.

They chose the latter; this led to a second problem. Whilst the designers knew exactly what parts of the game couldn't be blown to bits, players would have no clue and this resulted in a waste of resources, ammunition and explosives as the players tested everything to see what could be destroyed and what could not. It was possible in Geo Mod to actually dig into the ground for a distance and create impromptu rat holes to hide in and ambush enemies, new tactics evolved in that respect and certain areas of ground were made immune to the effects of weapons fire, rockets, bombs and high-explosives to stop the players from digging under an all important door or wall where they needed to solve a rudimentary puzzle.

It didn't stop us trying.

Geo Mod was the first system to actually simulate destruction on that level, before it we were actually tricked into thinking something could break. Take a simple wooden door for instance in some of the older games, there's nothing defining that door as a physical object in the game world, there are no statistics for the door, no weight, density or mass. It's just a rectangle with a texture on it. To make it look like you have broken it, all we do is swap in a new bit of broken door and then perhaps make it fall down, smoke and mirrors.

Over the past few years there have been many attempts at destruction in games, simulated destruction and so forth. John Woo's: Stranglehold was a game that actually used a simulation technology to determine bullet holes, destruction of environmental objects and so on. It worked fairly well but was still only a bare bones simulation.

LucasArts and Pixelux Entertainment worked on a proprietary material simulation and animation technology for two games, Star Wars: the Force Unleashed and the upcoming Indiana Jones game (that's still in development) - Digital Molecular Matter was the next step forwards in material simulation, allowing for true materials to be created without the need for a designer to do anything complex to get a material into the game. It is easy enough with a command line to apply a material to an object, glass, wood, metal and so on.

This YouTube video of a DMM castle was one of the earliest demonstrations of the technology. The simulated stone material has been applied to the object and boulders.

DMM Castle Video

The Force Unleashed however proved to be a let down in many ways, many press felt that the DMM wasn't used to its full potential and whilst bending metal and buckling certain doors appeared to be very effectively done using the system, it lacked simple little things that would have kept the suspension of belief. Blaster marks in the walls being created by DMM impacts, the lightsabre cutting into the metal and leaving scorch marks that don't fade.

LucasArts again tried to jump on the terrain deformation and destruction bandwagon with Fracture, an innovative title in several ways. Until you look deeper at it and find that again, like Force Unleashed, the technology isn't used to the best way. The terrain could be raised, lowered, blown into craters and basically that's all you got. There were some destructible environment parts but again, it was all keyed to specific locations and certain parts of the environment - the player had to experiment to find out what they could decimate.

Gears of War 2 contained Epic's own in-built simulated destruction engine in the latest iteration of their Unreal technology. Whilst not as impressive as DMM or Geo Mod it required the designers to think outside of the box to provide innovative solutions to impede the player's progress, since it was possible to blow chunks of wall and building away. Adding an inner sub-layer of metal struts and so on seemed to do the trick.

During all of this the Kings of Destruction and Sultans of Boom, Volition, have been beavering away for the last five years at their own answer to the problem. Aptly dubbed Geo Mod 2.0 this is a new breed of physics based destruction and simulation that worked so well, when the designers built their first structures on Mars in the game and applied the live physics simulation effects, they fell down under their own weight. Volition had to learn the ways of an architect and apply sub-structures and reinforcement techniques to all of their in-game objects, in essence they became architects and built virtual buildings that would work and obey all the rules of real world physics.

What they did however with Geo Mod 2.0 is make sure they said from the start, this is a physics based and object based destruction technology, not applied to the terrain, you can't blow the ground to bits like in Red Faction. They wanted to focus on letting the player tear Mars down and still keep the structure of their game world intact.

Geo Mod 2.0 (if you've read our preview from the demo) is something special, it does exactly what it says on the tin and it does it very well. The buildings are incredibly detailed in terms of architecture and design; they have metal struts, sub and super-structures to them. The material simulation in Geo Mod 2.0 allows the player to go wild with their destructive urges and as you destabilise a structure, physical forces come into play. Weight, mass, inertia and force are all applied. It can take just the slightest additional weight, from say a thrown sticky high explosive charge, to topple the whole thing down.

At one point I actually managed to bring a whole building down on my head by knocking into the support beam with my player. That didn't end well.

If you're interested in this kind of thing, there are a pretty good couple of videos here that outlines the destruction technology and showcases some of Volitions problems that arose from the implementation in their latest Red Faction game, Guerrilla.

video 1

video 2

As you can see, not only are the debris in the game calculated using stress based systems, they're also live objects. Any broken piece of stone, metal and so on has an effect in the game world. It can impact explosive barrels or the enemies/allies/player and set of a chain reaction of destruction. A large piece of stone can hurtle through the air and smash through the side of another building, if it has enough force behind it.

It is impressive stuff.