There are lots of ways to craft a sermon. Expository, Narrative, Historical-Redemptive, Mystagogical, Puritan Plain, Exegetical, Doctrinal, and Testimonial Preaching have stood the test of time and are viable options for preaching methods.
But not all of those methods are oriented toward the needs of the hearer. You can preach an absolutely water-tight, rock-solid Doctrinal sermon, but for many people in the pews (who didn't actually attend seminary), the whole thing will sound more like Charlie Brown's teacher than Good News.
The Episodic Method of preaching is designed for both the ears and eyes through playful creativity. Episodic preaching is a method of showing, not telling. In the Episodic Method, imagination is paramount. The Episodic Method encourages the preacher to be descriptive rather than prescriptive.
The theologian James Evans teaches that to be human is to tell stories. Thus, Episodic Preaching touches on what it means to be human by taking episodes of different stories and quilting them together to reveal a common theme. This method depends heavily on indirect communication or what we might call the inductive method of preaching - where imagination, rather than direct propositional statements, drives the listeners and invites them deeper into the text.
Think of Episodic preaching as a Topical Sermon that is developed and presented through episodes. Those episodes are stories from the Bible and/or specific verses related to the sermon's theme: all connected by a "rhetorical bridge" that's repeated throughout the sermon (sort of like the chorus of a song).
It's much easier to understand this form when you see it in action.