I'm toying with the idea of making at least one of the worlds in my Alkonost setting have "non-standard" technology with an Atomic Age (i.e. 1950's/1960's speculations about future spaceflight) flavor to it. The world in question, Laana, is strongly biased against AIs and most advanced electronics (and with a good reason - they were slaves to the Incunablis Machine Empire up until recently), and having analog electronics, hydraulics and a lot of clunky machinery - not to mention bulky fission reactors - would fit them very well and also make them quite unique.
The thing is that I also want them to be a minor interstellar power, and, therefore, would like them to have jump-capable ships. But J1 drives are TL9, and Fusion is available beginning from TL8, which makes the clunky fission plants redundant.
So what I have in mind is to make Laana TL7, with several elements of TL8 (in biology, agriculture and medicine for the most part) and with a few TL9 technologies (mainly jump-drives). Alternatively, they might be importing the jump-drives as 'black boxes' from Alkonost (the TL11 major power in this subsector) and jury-rigging them into their TL7 fission-powered, analog-system, reaction-driven starships.
What do you think about this? Have you done something similar in your campaigns?
