Monthly Archives: July 2008

JFK and Microphysics

Game physics are big these days. It wasn’t until today that I realized quote how much further we could go.

Most games with physics model big stuff only. Boxes and bodies colliding and bouncing around. It’s all very nice. But what about really nailing the feel of small-scale interactions? We don’t have the computer power to really accurately model physics for lots of bodies, but I played a game today that tries to models a very accurate ballistics model for just a small number of shots and targets.

It’s JFK Reloaded, a game where you play as Lee Harvey Oswald and try to recreate the assassination of JFK. The game is supposed to be about recreating the three historical shots, and either proving or disproving the official story of what happened. My interest was in the after-report of what you do during the shooting.

After you play, you get a shot by shot summary of what you did, with a 3D view of the president’s car and a line tracing the exact path of the bullet as it penetrates air, metal, or flesh. The bullet may change trajectory slightly as it passes through part of a car or person. It may hit the same person several times as it penetrates several limbs. This goes far beyond modeling wind and bullet drop.

I think other games could benefit from having some real effort put into their ballistics and microphysics like this. Most people think of having more debris and crates flying around when they think of advanced physics. But what if we could just do the same stuff we do now, but more accurately?

It won’t massively transform the game experience, but it could lead to lots of cool little stories, especially if it is combined with some kind of system to record your shots and allow you to actually see the trajectories of your bullets. Hitboxes aren’t doing it for me any more.

Finally, here is a cool video of stuff happening in slow motion to show you some other applications of the microphysics principle.

Finally, some rather historically inaccurate versions of the JFK shooting as played in JFK Reloaded. Where everybody in Dallas was on crack.
And another…

Weapon Meatiness and the Big Pipe

Patrick Lipo has an article up about making shooter weapons feel powerful. The fact that it includes actual videos from a number of shooters makes it a useful comparison.

We can never replicate the audio experience of firing a gun, because it is far louder than anyone will ever want to push their speakers to. Real weapons fire isn’t just heard, it’s felt. If you’re close to the weapon you can sense the compression in your chest. If you do this regularly, you will lose your hearing.

As game designers, we need to try to recreate the feeling of holding onto a piece of hot, precision-engineered gunmetal full of violently moving machinery and barely-contained explosions, whipping out fifteen lethal chunks of metal every second. Furthermore, we need to replicate this feeling in a dude sitting on a couch, with a game controller in one hand and a bag of potato chips in the other. It’s an interesting challenge, if one we can never truly succeed at

Back when I did Elemental Conflict, I considered weapon ‘meatiness’ to be one of the most important parts of the game, and spent a long time experimenting with different methods of making the weapons feel nice and throaty. Using some original methods, I got some pretty good results. I’ve been was surprised that many of these ideas have never appeared in any game since then. So, I present them to you now.

Reticle SnappingĀ 

The first was to change the way the player’s target reticle works.

Most games have a static target reticle that is permanently locked in the center of the screen. Some games, like Counter-Strike, show the reticle expanding as you fire to indicate that your accuracy is decreasing. This is useful to help you understand why you aren’t hitting anything when your reticle is four inches wide, but it doesn’t do much to make the weapons feel visceral.

For Elemental Conflict, I developed a system whereby the target reticle snaps to a slightly different, randomized position whenever you fire your weapon, before sliding back to the center of the screen. As you fire continuously without a break, the reticle moves more and more with each shot, until you eventually it is flying all over the screen and you can’t hit anything that you’re not face-to-face with.

If you are a really good player, you can actually compensate for the reticle snapping by moving your point of aim. As you get better, you can compensate faster and maintain higher rates of accurate fire.

It felt great because every shot had that added kick of a moving HUD element right in your field of vision, and it communicated similar information as the expanding reticle system.

Weapon Model SnappingĀ 

To make it feel even more physical, I also offset the weapon model by a small amount corresponding to the current target reticle offset. So when you fired at a high rate, the gun would begin to buck wildly in your character’s hands more and more with each shot, until it was very clear that you were just barely holding onto this screaming piece of metal.

This, combined with the moving reticle, gave a strong sense of holding a physical object which is imparting strong, hard-to-control forces into the world. Having fired a few machine guns since then, it does much more closely resemble the reality of how these weapons feel than the expanding reticle system.

The “Big Pipe” Philosophy

During the design of EC, I developed the philosophy of the “big pipe”.

In many games, it feels like you can only deal out damage in a trickle, even if you have thousands and thousands of rounds in ammunition in reserve. This feels like you’re pouring water from a huge tank out of a small pipe. It creates an irritating feeling of impotence. All you do is open your spigot as wide as it will go and pour and pour but nothing much happens. The tank never empties and nothing gets very wet.

Real life, and EC, have the “big pipe”. A modern military unit can easily exhaust all of its ammunition in an extremely short period of time. Modern weapons can fire at 800-1000 rounds per minute. A soldier carrying 300 rounds of ammo (ten magazines, quite a lot) could fire that all in under half a minute if we ignore reloads. Even with reloads, he can still unload it all in under two minutes.

That doesn’t matter, however, because a normal assault rifle will fail due to overheating long before then. Even a SAW machinegun requires a barrel change every couple hundred rounds. Very rarely will a real soldier be limited by his weapon’s rate of fire instead of his ammunition reserve.

So why do these weapons fire so fast? Because (among other reasons) if a moment ever comes where a soldier does decide to go all-out (say, he turns a corner and comes upon a group of enemies), his destructive capacity can be huge. It is unsustainable, but it is huge.

This is the “big pipe” feeling. It makes you feel like you have tons of power, but only spend most of your time without using it in order to conserve resources. When a tactical coup does happen, you can take advantage of it. Contrast this with the feeling of many games, where you pound an enemy as fast as you can at close range and it still takes him 10 seconds to go down. It’s like grinding him to death with a cheese grater.

To create the big pipe feeling in EC, I added a shoulder-mounted grenade launcher that allows a you to simultaneously fire your weapon and lob grenades at a very high rate. This created a very high limit for the destructive power of a single player. I could only balance it by making sure that you could easily exhaust all of your ammunition very quickly if you really ran EC weapons at full blast. If you do make that sacrifice, however, and accept being without ammo for the rest of the round, you are rewarded with the ability to launch multiple cluster-bomb grenades while firing a machine gun at 900 rounds per minute and simultaneously flying through the air on top of a rocket-powered booster pack.

You can see all of this in the second half of the Elemental Conflict video.

Real Power Versus Audiovisuals

The final point I want to add is that the feeling of a powerful weapon doesn’t only come from the audiovisuals. A gun with the best muzzle flash, sound effects, and impact animations in the world will still feel weak if it takes 20 point-blank hits to kill a weak-looking enemy.

I noticed this mostly in Bioshock, because there are many enemies in that game who are visually identical or very similar, with drastically different numbers of hit points. Fighting six weak wrench-wielding splicers with the pistol makes it feel powerful because you can gun them down in one or two shots each. Fighting one wrench-wielding splicer who has the exact same audiovisuals but takes 9 rounds to go down makes the pistol feel wimpy, regardless of the sound effects. I think this is part of the reason COD4 and Counter-Strike weapons feel so powerful. Every enemy goes down in the first few shots.