The Sounds of PopCap, Part 1: Bejeweled Twist
There's nothing casual about the love people feel toward PopCap games. But what exactly is it about its games that makes them so damn hard to put down? Of course they're fun to play. But so are thousands of other games. No, there's something in the "special sauce" at PopCap, and I suspect that the audio feedback -- the sounds of PopCap games -- have something to do with it.
To get to the bottom of this aural issue I talked with the makers of Bejeweled Twist, Peggle and Plants vs. Zombies to find out how they use sound to keep us playing. Jason Kapalka (PopCap co-founder, chief creative officer and lead designer on all Bejeweled titles) explained that his designers put an inordinate amount of thought into the bleeps and bloops their games make, because "a simple sound like the gems matching in Bejeweled will be heard hundreds or thousands of times during a game, so it had better not get irritating!" An argument could be made that the sounds of PopCap games do more than avoid irritation -- they add to the compulsion by being pleasant in the extreme.
Jason Kapalka talks us through many of the sound effects from Bejeweled Twist:
The sound: Chirp when you match gems.
Jason Kapalka: This is pretty similar to the sound we've always used since the first Bejeweled. I don't even recall exactly what this sound is or where it came from, but for some reason it's just satisfying to hear over and over.
The sound: The rising pitch when you get more than one match.
Kapalka: Rising pitch for combos and cascades is one of our oldest, simplest and most effective sound tricks. I'm sure a psychologist would have some theories about why this makes people feel good ? all we know for sure is that the rising pitch creates anticipation and excitement, so we tend to use this in every game that has combos (like Peggle, Chuzzle, etc).
The sound: The satisfying clack sound when the gems fall.
Kapalka: As with the matching sound, the gem-click is one of our oldest Bejeweled sounds, that really hasn't changed much since the old days. It's not a realistic sound of gems clacking. I think it was derived from pool balls clicking together, then sped up and otherwise tweaked. Pool balls are a very satisfying and familiar sound to people. We also used them for the stone spheres clacking together in Zuma.
The sound: Spinning and moving the reticule have subtle sounds.
Kapalka: Audio feedback for little things like this are important to let players know that the game is responding to their actions. But you have to be very careful with sounds like this, because you hear them hundreds or thousands of times during a typical game, and if they're annoying at all, you'll rapidly go insane listening to them over and over.
The sound: Explosions of bombs.
Kapalka: Explosions in Bejeweled games are almost always a good thing, not a bad thing, so you don't want a sound that alarms people, as if their car just blew up or they were being attacked by bazookas. But you still want a satisfying and beefy blast when you blow something up. We tend to start with some stock explosion sound and then muffle and soften it a bit, while adding some shattering-glass sounds to simulate the gems breaking up.
The sound: Multiplier goes up; sounds like some kind of device powering up.
Kapalka: This is one of my favorite sounds from Twist. Again, it's a completely abstract sound that's not based on any real-world recording. It's some kind of 8-bit synth effect simulating an old arcade game that was then run through a variety of speed and pitch shifters to make it sound like it's revving up, then lathered with reverb.
The sound: Chirps as scores pop up on-screen after a combo.
Kapalka: We favor the pinball school of sounds, where you're always hearing lots of "good" sounds to encourage you to keep playing, and only very rarely a "bad" sound. We found you can make a game very discouraging to play by adding just a few really nasty-sounding buzzers when people make an illegal move, for instance: You want a negative sound to let them know they made a mistake, but it still needs to be reasonably pleasant.