Xbox.com: There are a lot of racing games available for Xbox right now. What is it about Forza Motorsport that differentiates it from games like Project Gotham Racing® 2 or RalliSport Challenge 2?
Greenawalt: Forza Motorsport is a pure simulation engine wrapped in an accessible motorsport-based game world. With realistic assists, fantastic tactile control, and player feedback, gamers will be able to pick up and play. However, because of the depth of the physics, the player can continue to learn about the car and travel the path of mastery as a racing car driver. Every car is a new experience. Weight and friction transition realistically, allowing great racers to express themselves through their driving. Meanwhile, we’ve employed realistic traction and anti-spin assists that will allow inexperienced drivers to compete and be successful.
Our tire and suspension model is extremely realistic. We partnered with Toyo tires to get real-world data on production and race tires to model in the game. Our tire model exhibits pressure, wear, heat, and load sensitivity. Tire friction is also affected by the rubber groove and marbles on the road.
We worked with an engineer from Ferrari’s F1 program to completely simulate real-world suspensions. When configured to simulate a double “A†arm suspension, the track decreases as the suspension compresses and negative camber is introduced. In turn, the camber and weight affect the tire heat and thus pressure. Most consoles simply do not have the power to compute what we’re computing for the physics and still render a game.
Xbox.com: We’ve heard that some members of the development team are hardcore racing fans. How deep is their involvement with the sport, and how has that influenced the design of the game?
Greenawalt: We’ve got a very passionate and well-connected team. Some are professional racers, while others are hardcore racing fans. Monday morning water-cooler talk invariably revolves around the weekend’s televised F1, ALMS, MotoGP or SpeedGT race … or our latest speeding ticket …
One of the developers was fifth on the wait list for an Enzo. When he found out the Seattle Ferrari dealer was only going to receive three, he dropped off the list and ordered a Lamborghini. This same developer drives his 360 Modena at its limit at track days—and on his way to the office. The first time I met this developer, he had just climbed out of his car at Laguna Seca, where he placed seventh in a Star Mazda open-wheel race.
One of our artists is a professional Rally driver. Two team members have raced in open-wheel leagues. We have several accomplished motorcycle racers. We’ve also got some serious tuners and car collectors. A recent addition to the team has an AC Cobra replica making more than 600 hp in a 1500lb body. The rumble from that car will rattle your teeth loose. When this project began, our planner had an RX7 with a suspension so tight that you needed kidney dialysis after a ride in it. Lately, I’ve been working with the design lead for PGR 2 on my S4. On the outside it’s pretty stealthy, but I assure you that it’s got boost. It still can’t compete with his Viper ACR, but a project car can’t be built overnight!
Most of the team is addicted to going fast. In developing a simulator, you couldn’t ask to be surrounded by better subject matter experts. Whether the subject is car tuning, car upgrades, or track layouts, I always have the best resources sitting just down the hall from me.
Xbox.com: Were there any racing games that inspired your team? If so, what were they?
Greenawalt: Obviously, the GT series has been a huge influence on this team. Personally speaking, the original Gran Turismo was the only reason I bought my first console. Without that game, several of us probably wouldn’t have become involved in this industry. Polyphony has created a great series.
I’m sure many will see the influence of SEGA’s classic Ferrari 355 coin-op game in our E3 presentation. We have a 355 machine with a triple-screen set up in the lobby of our office. The art lead and I still love to play the old Sportcar GT game for the PC. It was a great blend of simulation and accessible fun. It also had really cool cars and real-world tracks.
A few team members participate in PC online racing sim leagues for Papyrus’ Grand Prix Legends and NASCAR Racing 2003. These games have a small, but fanatical following. Some of these communities have created third-party telemetry and replay analyzer programs as well as huge content mod packs. Recently, one of my buddies showed me an online league based on a version of F1 2004 that was mod-ed to have FIA GT and ALMS cars and tracks. That looked pretty fun … but extremely challenging. These hard-core communities are a better source of inspiration than any game could be.
Xbox.com: Describe the gameplay of Forza Motorsport. Is it pure simulation? Will gamers be able to “pick up and play†a single race as well as play an entire season in a career mode?
Greenawalt: Its career is a racing sandbox—with hundreds of hours of customization and racing gameplay. The game’s unlocking and progression structure is a blend between open-ended exploration and linear leveling.
In Forza Motorsport, you can collect and personalize cars from more than 60 of the world’s top manufacturers. These cars can then be driven in hundreds of races, which are broken down into a dozen different real-world race types. If hot-lapping is your thing, have at it. If you prefer point-to-point racing, we have that, too. Looking for standard circuit racing? We have lots of that on both real-world race tracks and stunning fictitious race tracks. Forza Motorsport also contains interesting race types plucked from throughout the world of motorsports, so it doesn’t limit you to a linear path. You can gain money and prestige whenever and wherever you want.
Xbox.com: Realistic artificial intelligence seems difficult to achieve in games. How is the development team ensuring the quality of the single-player experience?
Greenawalt: Everyone talks about A.I. in racing games. Rather than spitting out features, let me simply frame our approach and let you draw your own conclusions. You know when I was saying that we’ve assembled a team of all-stars? I wasn’t kidding. We actually have several high-level developers working on our A.I. alone. Our main A.I. developer is new to games, but incredibly experienced in A.I. He’s a PhD A.I. developer from Microsoft’s research division. In the past, he’s worked on robots and learning A.I. systems. He’s teaming with our research division in Cambridge, England, to approach A.I. from a completely different angle.
It’s really cool to see a group approaching this problem from a completely new angle. Rather than giving the A.I. different car physics, a predestined spline, and random seed to mix it up, these guys are creating thinking A.I. that drive Forza Motorsport’s remarkably complex physics engine. Even our A.I. difficulty levels are based on learning artificial intelligence. Lower-difficulty A.I. makes human-like mistakes, such as late braking and late apex-ing.
It’s sort of hypnotic to watch the A.I. learn. I’ll tune a new car and give it over to the developer to train the A.I. driver. The A.I. driver then takes over the car and starts putting together laps. The laps get better and better as the A.I. tests out the new car’s limits. After a couple of laps, the A.I. is putting together really fast times in the exact same car physics the player drives. What’s even more amazing is that the A.I. doesn’t have to relearn on other tracks. It just applies what it knows about the car’s abilities and starts churning out hot-laps on the new track.
If you don’t work in this industry, you might not understand how unprecedented this is. Every other racing game I’ve seen has used slightly different physics and predestined splines for the A.I. The artificial intelligence in Forza Motorsport is truly intelligent.
Xbox.com: How will physics and damage modeling affect gameplay?
Greenawalt: The on-track experience is a simulation. However, we have customizable levels of difficulty, in the form of damage, assists, and opponent skill, that allow you to alter your experience.
Forza Motorsport features performance-affecting damage. However, realistic damage can be extremely punishing. Therefore, we’ve integrated damage into the difficulty system. You can play with fully simulated damage, limited damage, or simply cosmetic damage.
Challenging yourself will increase the rewards for winning. With the difficulty settings at default, I expect most players to be able to pick up and play the game successfully. Meanwhile, they are encouraged and armed to grow their racing skills.
Xbox.com: To what extent will players be able to customize their vehicles?
Greenawalt: The upgrades fall into three buckets: appearance upgrades, performance upgrades, and performance tuning.
The cars, from more than 60 manufacturers, include some hot sport compact cars like the Dodge SRT4 and Nissan 350Z. We’ve licensed real-world body kits for the hot tuner cars. These are the appearance upgrades. Based on the number of kits we’ve created, we have several billion possible visual car permutations. Of course, we are a simulator, so each of these kits has weight and aero components to them as well. We also have an extremely powerful paint job editor. This editor allows you to place decals and vinyl primitives all over the car. You’re not limited to specific shapes and locations, so you can go ahead and freestyle.
As for tuning and performance upgrades, let’s just say, you’ve never been able to do the level of tuning available in Forza Motorsport—ignition timing, boost pressure, fuel ratio, not to mention the standard tire pressure, camber, caster, toe, gear ratios … In the upgrade category, Forza Motorsport includes everything you need to transform your stock performance car into an absolute track monster. And, of course, all of the parts are based directly on real-world upgrades you’d find on the track, from cat-bypass and cat-back exhaust to centrifugal superchargers, large surface area intercoolers, cold air intake, and triple-plate clutch.
Xbox.com: Anything you’d like to add in closing?
Greenawalt: This game is made by car freaks in the hopes of infecting the world. If you know a ton about cars and racing technology, you’ll appreciate the depth. If you’re a racer, you’ll be able to express yourself in the incredible physics engine. If you don’t know much about cars, but still get saucer eyes when you see a bright red sports car or a hot tuner car rolling down the strip, you’re gonna love this game.
