Gone are the days of radio dramas. Initially developed in the 1920s, these were the original bits of broadcast entertainment. I don't know a ton about the history and downfall of the audio play, but I presume it has to do with an invention called the "tee vee."
The modern era has returned remnants of this golden age of audio. The artistry and sonic quality being brought forth in podcasts continues to evolve.
So here's what someone needs to do: Picture (is this the right word?) an audio mystery. Perhaps you're solving a murder, a la the classic "murder mystery party." But it's all sonic. Clues are embedded in the sound itself.
The user is listening for clues as they follow the story. They're listening for a wavering voice, a lie stated, a noise in the background. As they correctly navigate the story, more information is revealed. If they misstep, they may never find out what happened.