Eye tracking is a feature that's rarely used in games, because it requires a specialised piece of hardware like a Tobii 4C eye tracker. However for those that do use it, it can deliver some interesting effects. Like in the case of Frictional Game's Soma, which has now added support for eye tracking hardware.
New additions include the torch following the player's gaze around the game, triggering environment-specific effects and zooming in on where the player looks to subtly increase the claustrophobic feeling of the environment.
Perhaps the creepiest addition with such a system though, is that the sentient creatures within SOMA's underwater world actually move when you aren't looking at them, so while contending with your own sanity, you'll need to balance keeping an eye on them so they don't jump on top of you at the first sighting.
Although SOMA is one of the few games with serious eye tracking support, a number of games are adding what's called Foveated rendering, which can reduce the need for a graphics card to render a whole scene at the highest detail levels, which could help all of us have better performing PCs in the future.
