Yep, engines too... just couldn't think of any sort of "polaron engine"
I was also thinking, with some of the stuff like nuclear, fusion, ion, antimatter, etc. reactions, perhaps there should be a tech area for uncontrolled reactions and a tech area for controlled reactions that requires the maximum level of the uncontrolled reactions tech; the uncontrolled reactions would provide bombs and missiles (and maybe Orion drives), while the controlled reactions would provide beams, reactors, and engines... after all, we do have the tech to build fusion missiles (do we actually have any or are they all regular fission warheads anyway?) but not fusion reactors yet since that requires a controlled reaction...