He’s well known to fans of the U.S. indie pop band fun., which won Grammys for Best New Artist and Song of the Year for “We Are Young,” the group’s soaring hit with Janelle Monáe. As its energetic frontman, Nate Ruess was credited with giving fun. its swagger and gleefulness—even in the face of downbeat subjects. On his solo debut, the 33-year-old mixes dark tracks with infectious songs that have all the optimism of “We Are Young.” “AhHa” is a little of both, shifting from a bombastic opening into a moving account of struggling with depression and getting saved by music. The title track is a sweeping confessional with operatic overtones. But the album’s best song is “Nothing Without Love,” in Ruess professes how his heart has been won over (he’s currently dating designer Charlotte Ronson). Starting out with a simple piano, it builds to a joyous crescendo. Pure pop—exactly what Ruess has done best with fun.