Siddhartha has genre Speculative fiction. Speculative fiction has examples: Wake
[Human]: Could you recommend books similar to Siddhartha?  [Assistant]: A few books in the same genre are Wake, The Thief of Always, The Sweet Far Thing, and The Neutronium Alchemist. [Human]: Who wrote The Thief of Always? That one sounds interesting.  [Assistant]: It was written by Clive Barker and was originally published in 1992. [Human]: What else has Clive Barker written?  
He also wrote Abarat, The Great and Secret Show, and Imajica.