At Play, Vol. 4 is a compilation album from the Canadian progressive house musician deadmau5 and the fourth of the At Play series. Like the other "At Play" albums, this installment contains tracks previously released on the 2006 album Vexillology and the 2007 EP Full Circle.

At Play, Vol. 4 also includes the track "GH", which was "created in the days before Random Album Title." The track also reuses a sample from the track "Sometimes I Fail". Like with At Play Vol. 3, deadmau5 claims to have nothing to do with this volume of At Play. The track "1891 [Minimal Remix]" from "Full Circle" is renamed to "1891" on this album.

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