Complex sentence: Teddy accuses Leonard of creating an unsolvable puzzle to give himself purpose and points out that since "John G" is a common name, his search will be indefinite, as even Teddy himself has a John G name.
Split into simpler sentences: Teddy accuses Leonard of deliberately creating an unsolvable puzzle to give himself purpose. He points out that since "John G" is a common name, Leonard's search will be indefinite, as even Teddy himself has a John G name.