My favorite is Demon's Souls, of the Dark Souls trilogy my favorite is Dark Souls 2, while among Elden Ring, Bloodborne and Sekiro my favorite is Sekiro.

Demon's Souls on PS3, I played it in 2010 and managed with a lot of effort to overcome the first area and beat the first boss and shortly after I abandoned it, then in 2013 I started it again and managing to understand how the game worked I finished it for the first time.

I think the definition of a masterpiece exists for a reason.
In my opinion people use the word masterpiece to indicate a game that they
really liked, that emotion him, with which he had fun etc ... but the emotions,
the fun, the boredom etc ... They are subjective things and vary from person to
person. I do not think I have the necessary skills to define which game is
objectively a masterpiece or which are masterpieces in other arts, but the
definition of masterpiece is: a work of art such as a painting, movie, book,
etc. that is an excellent, or the best, example of the artist's work, for video
games a masterpiece should be a game that excels in all its parts (I have
almost), for example a game that is perfect in gameplay and in its other
parts, or the best work of an author could be considered the one who created a game, a mechanic etc ... which then became a reference point and/or revolutionized the video game industry.

Nobody, because for me the subjective masterpiece does not exist and for that reason I do not consider any videogame a masterpiece.