The free-to-play rhythm game, Groove Coaster Zero, adds a new Global Hits Pack for you to jam along to during your wild roller coaster ride. The new music pack is available through in-app purchase for $4.99, featuring Lady Gaga (Poker Face, Bad Romance), LMFAO (Party Rock Anthem), and Gwen Stefani (What You Waiting For?).

So, as Gwen Stefani’s song title mentions, what are you waiting for?