A lot of folks are listing their favorite games but this is the one that truly fits.
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Unusually long development time by a studio known for DnD-simmiliar RPG games getting the next installation for the series that defined the genre.
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Cast voice actors for several years, ones that are still playing their characters on a variety of platforms.
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Just chock filled references to DnD lore, cute in-jokes, and faithful updates on old characters.
Everyone involved clearly loved it!