2046 is loose sequel of 'In the Mood for Love'. Both are from same director and have same lead actor. Both have beautiful music and many more similarities.
2046 is the sequel of In the Mood for Love. Both explore love and loss, and change of feelings overtime. You don't really need to watch in chronological order as each can be viewed as a separate.
Set in contemporary Hong Kong, a disillusioned hitman embarks on his last hit but first, he has to overcome the affections of his cool, detached partner he rarely sees. Thinking it is dangerous and improper to become involved with a colleague, he tries to find a surrogate for his affection. Against the sordid and surreal urban nightscape, he crosses paths with a strange drifter looking for her ex-boyfriend and a mute trying to get the world's attention in his own ways.
Both are beautiful, sensual and aesthetic movies that were both directed by Wong Kar Wai. Both also seem like character studies of the female lead where the male lead takes more of an observer role (2046 explores the male main lead more). The romance stays unfullfilled as well. Gong Li acts in both.
