Is there any difference between adept at and adept in? Should you believe it utterly depends on the context, I would be grateful if you would at least provide a brief explanation of how it depends.
As seen in this Google Ngram search, adept in is the more archaic usage, while adept at is more modern.
Furthermore, adept was historically used as a noun, as in: "He is an adept in the game of chess." Currently, adept is more commonly used as an adjective, as in: "He is adept at the game of chess."