How is this fundamentally different from using the phone's vibrate? I get that technologically it's a zap more so than a buzz, but from a user perspective, could I even tell the difference? Just seems like a rather boring feature. If vibration feedback truly made a game better, wouldn't they have been including that for the last however many years via vibrate?
Many phones use a tiny electric motor rotating an eccentric mass, just like a clothes washing machine spinning an off-balance load. The frequency (rate of rotation) can change, but it is difficult to control the amplitude because the mass (washing machine load) stays the same.
A linear actuator is also a magnetic motor, but instead of rotating a mass, it oscillates a mass back and forth. Here's an X-ray video of the iPhone 7 actuator in action.
As it's a mass attached to a spring on each side, it has a natural resonant frequency where it works the best, which is usually about 175 Hz for haptic actuators.
But while the frequency can't be changed, the amplitude (how far it swings back and forth... like the volume of an audio waveform) can, which is considered an advantage for creating various haptic feedback sensations.
Because linear actuators can do better haptics than rotating actuators, companies like Nokia, LG and Samsung switched to them around 2012. Apple finally switched from eccentric mass to linear actuators with the 2014 iPhone 6.
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For examples of the effects possible, this blog article from 2012 mentions some of the things an S3 owner could set up and feel:
"The Samsung Galaxy S III has finally arrived, and its got an advanced feature called Auto Haptic that uses vibration to create engaging physical response in downloaded 3rd party apps.
"With Auto Haptic, you can feel the sling stretch as you fling an angry bird and feel the impact of a grenade explosion in a first person shooter game (be sure to check out our list of recommended apps that work great with Auto Haptics!)
"Auto Haptic is based on Immersion’s Reverb technology, which automatically creates haptic effects by monitoring the application’s audio track.
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That last line is important, because Immersion has many base patents on haptics. Samsung Electronics has had a license with them for a long time. In fact, they were the very first Immersion cell phone client back in 2004. They've used the technology in phones, CD players, etc.
When Apple later brought out their own haptics library, they were sued by Immersion. See these articles here in MacRumors:
Immersion files patent infringement lawsuit against Apple
Immersion files second lawsuit
To be able to (legally) do some of the better effects, it's quite possible that Apple will have to join everyone else in licensing Immersions's patents. The question of whether or not these patents should've been granted in the first place, is another topic.