Don't call it a comeback, call it an explosion, as I Got a Boy is the first album in over a year from the K-pop crew Girls' Generation, and their first since their Japanese-language splinter group, Girls' Generation-TTS, returned to the fold.

Even with the nine-piece lineup back in place and the lyrics returned to primarily Korean, the group still does it big and adds a "Time Machine" concept to the album as genres from the past are explored.

"Romantic St." flies back to the '40s with its cute re-creation of swing time, while "Promise" goes for '90s R&B with a drum machine and grand piano to underline its story of heartache.

Don't think "Dancing Queen" is the '70s ABBA song, because it's a worthy redo/rewrite of Duffy's 2008 hit "Mercy," and if you want the sound of 2013, check the elaborate single "I Got a Boy" as it mixes dubstep, pop-rap, and EDM for a busy highlight.

Fans will embrace it with open arms, while mega-fans should also clear some shelf space since the physical edition of the album was made available with ten different covers, one for each member of the group and then one with the whole crew.