The Devil’s tuning fork is an old optical illusion. It gives the impression of a three pronged fork when looking at its tip, but the middle one disappears when looking at its base. Here’s how it looks:

A tuning fork is also a real-life item used by musicians, professional tuners (they exist), and even watchmakers. They resonate at specific, constant frequencies while letting out a low tone, giving tuners a reference point to tune instruments to. Combining these two concepts, a small team from DePaul University made a game titled The Devil’s Tuning Fork.

The game opens up with a short animated sequence portraying a world in the middle of a children’s coma epidemic. No details are given to cause, just the fact that it’s happening everywhere. Players are then standing in a dark hallway, where waves of light quickly illuminate the shape of the room. After a quick tutorial, players are then given the Devil’s tuning fork, which lets them send out a wave of light with a ding of the object. Mechanically, this game could have been called Bat-Man, where players take control of some half-man half-bat creature who uses echolocation. But the developer’s chose to go a more sinister route, as exploring the grand, dark hall also includes picking up animated stuff animals that hold the souls of children; their tiny voice echoing through the dark is quite terrifying.

A few puzzles that incorporate platforming and reflecting things off mirror are included, but the game’s main draw is its visual effects. Thankfully, the game is freeware and you can download it to your PC by going here.