There's actually two big surprises for me from last year: Ghost of Tsushima and The Pathless. If you told pre-2020 me that Tsushima would be not only my favorite open world game ever, but also my favorite game from last year, I would call you a crazy dumbo. As for The Pathless, I did not expect it to make me feel like I'm playing a game directed by Fumito Ueda, and the game just resonated on a much deeper level for me than I would have ever expected.
Speaking of Fumito Ueda, I already mentioned in this forum before that I recently played Ico for the first time, and considering my expectations from what people said about the game, I certainly didn't expect that it would immediately become one of my favorite games ever.