A lot of "talking-as-science-action" here, the narrative filled with hypotheses, theories, deduction, lucky guesswork, all in the guise of planet-scaled detective work: what killed the Draconians? There's a kind of brainy, international conglomerate / United Nations, post-"Star Trek" feel to it, but the situation back on Earth feels a lot less stable, more draconian (this plays into multiple fates in the book). Was the book written on the basis of a pun? Could be.
At any rate, I found the book a good enough, fast enough read, kept waiting to see what new discovery would unfold, what new mystery would deepen, but ultimately never quite invested enough in the characters (and certainly not the lead, Ian Macauley, who is borderline insufferable most of the time - written to be that way, but ugh). Most of the other characterizations were fairly flat, one-note affairs, and though each was apparently the top of their gene-pool (a major plot point), they just seemed there to fill a plot-point, not as a mechanism by which Brunner might develop more psychological, psychosocial themes with greater complexity. The ending was dismal, but I didn't really care enough for it haunt me later.
Late-'60s to 1970s science fiction can be pretty hit-or-miss for me, though I've at least two shelves of books from the period by names I know like Brunner, Robert Sheckley, Brian Aldiss, Norman Spinrad, Joanna Russ, Samuel Delaney, Gene Wolfe, Ursula K. Le Guin, Barry Malzberg, some I've read and forgotten, others I'll read and forget. A few I'll come back to. On that scale, "Total Eclipse" has been sitting there for a while now. Glad I read it. Won't come back to it. Not at the level of "Stand on Zanzibar," an altogether superior, if ultimately also dour, take on humanity's tendencies and fate.