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