A tour de force of lyrical, extravagant prose, the slim novel “This is How You Lose the Time War” packs in more phantasmagoric action and time-travel magic than most hard sci-fi books of three times the length. Red, a time manipulating agent of a mechanistic future, and Blue, a similar agent for an organic future, tussle across time lines in a dizzyingly sketched multiverse, before commencing to exchange covert letters of challenge and then admiration and then more. The two authors, both feted under their single names, concede no ground to the reader, throwing us into a barely comprehensible brew of worlds and times and technologies. Not a sparkling word or phrase is wasted. I’m still reeling days after gasping through the time-twisting complexity of a double climax that had my jaw dropping. I’m reminded of the times of Samuel Delaney, the sheer joy in the weirdest of worlds drawn in poetry. Amongst the best science fiction I’ve read this year.