Great & great
The Immortal and The Evergreen!!

Both of these games were written about in detail in The Mammoth Book of the World's Greatest Chess Games (editions 1-4). That's where I first learnt about these games. They are definitely masterpieces and it's hard to understand all of the moves without good annotation.
Dear Chess players,
As you may know one of the best players of all time is Adolf Anderssen. He has played many games in his life but the 2 most devastating games which is known to nearly ever single chess player is probably these two:
The Immortal Game: