Yeah I think all of those miss the mark pretty widely.
Shakespearean -ish dialog
spaghetti western -ish atmosphere and action
probably the nearest thing to it I've seen is Aguirre, Wrath of God
http://www.imdb.com/title/tt0068182/
Honestly, though, this is in a league of its own. Worth bearing in mind its director also did High-Rise and Free Fire.