Answer:
Nostalgia means "a yearning for the past," as said in wikipedia. It is also the name of a Nintendo DS game, which is about a boy from London named Eddie, goes on an adventure with his companions, Pad, Melody, Fiona, to find the missing templates that contains Fiona's memory. It is later revealed that the templates is the key to Asgard; the Cabal, and the Exploration Agency are fighting to get the key. In the game, you can travel to places such as New York, Japan, etc, to find these templates. In the beginning of the game, Eddie becomes an adventurer, and befriends Pad in the beginning, to find his missing father.