There has been no shortage of Deep Purple compilations over the years, but unlike some of the British hard rock legends' contemporaries (Sabbath, Zeppelin, etc.), they've managed a fairly consistent stream of output since their 1968 debut. Rhino's A Fire in the Sky, a 40-track career retrospective that includes at least one song from every studio album through 2013's Now What?!, is easily the most comprehensive anthology that the band has released to date -- a more manageable, largely singles-oriented 20-track version is also available, as is a triple-vinyl edition. Despite cycling through too many lineup iterations to mention, the band has consistently adhered to the heavy blues-rock foundation that made career highlights like "Hush," "Smoke on the Water," "Highway Star," and "Woman from Tokyo" so essential. Mid- to late-career offerings like "Perfect Strangers," "Call of the Wild," "Rapture of the Deep," and "Hell to Pay" may lack some of the bluster of those classic rock radio staples, but they still feel vital, suggesting that the key to hard rock longevity is sometimes just staying in the game.