Waterworld and Postman were actually very good movies that both suffered from many conjectures (too much marketing for the first one, deceptive marketing for the second).
Waterworld had more flaws because of the artistic dispute between the director and Costner, but it's really difficult to say anything thoroughly negative: funny villain (Denis Hopper is brilliant), believable world-building, good pace, entertaining, interesting enough and beautiful scenery.
The director's cut has officially been released this year (yes 2019!). Do you know why? Because the film had fans that kept sharing illegally the notorious fan-edit version (merge of the TV scenes with the theatrical version) over the years.
However I wouldn't compare Waterworld with Shenmue too much. Waterworld only executed well a formula with some original variations. Shenmue was revolutionary.
Postman is worthier the comparison. First reason because Postman is truly a great film. Second reason, it was really innovative in the way of viewing the apocalyptic genre. While Waterworld, Mad Max and other clones were rather pessimistic in their depiction of humanity, Postman praised the social unity, the "keeps your friends close to you" at nation scale.
Amazingly, Postman shares many ideas with Death Stranding (enthusiasm for citizenship, social motivation for rebuilding, story centered on postmen, addiction to help others).
I recommend to read the
opinion of David Brin, the original author of the Postman novel, if you wonder what the film aimed to convey and why it was badly received at the time.