"One by One" is a terrific example of scary audio theater. It's a Halloween story, where pretend horror gives way to actual disaster. The setting is a radio station, and the show does a fine job of creating an oldies station in detail: station staff, call-ins, stagey sound effects, and an elderly host. As this review notes, that lead performance is excellent.
There's also an impressive engagement with different types of horror technologies, from an embedded classic of Canadian radio drama to engagement with online media.
It's created by Electric Vicuna, whose site seems to be down now.