Re:Ask HN: What are the best Sci-Fi books you've ever read?
by webmaven on Sunday July 15, 2018 @03:21PM
(#17536577)
Rick Cook's "Wiz" series (SV programmer transported to a fantasy realm, invents programming language for magic, hijinks ensue) meets your criteria (fun, lighthearted, new ideas), I think:
https://www.goodreads.com/series/43084-wiz
Spider Robinson's "Callahan's" series is also great, especially if you like puns:
https://www.goodreads.com/series/49629-callahan-s