injygo

The last book I fell in love with was Devices and Desires by K. J. Parker, which is not BDSM erotica despite the name; it's a fantasy (?) novel which has no magic and apparently physics identical to our own world, just different cultures and people. (It might be an alternative history novel but it doesn't appear to be; if it is it's very divergent and doesn't push the historical side.) Anyway, it's a lot of technology and world building and characters and a little politics and military stuff. It starts with an empire that is mostly commercial in nature; mostly exporting rather than ruling directly, very regimented socially and economically (appears to be a planed economy, not a capitalist one), of roughly industrial revolution level technology, but no gun powder. This culture maintains power by keeping their technology secret by not letting anybody who knows tech secrets leave. They also don't allow innovation or variation of any kind except under very controlled and regimented contexts.

But when a trained engineer is caught violating those rules against innovation and escapes execution AND the empire and flees to the adjacent, feudal countries, the entire world is gradually thrown into chaos as he plots to rejoin his wife.