Some of the album's guest musicians include: drummers Mick Fleetwood, Jody Stephens, and Pete Thomas; guitarists Richard Lloyd, Robert Quine, and Ivan Julian; keyboardist Nicky Hopkins,;[5] and violinist Byron Berline.

Sweet told Spin magazine that the title meant "whatever is inside you that someday might explode, and maybe you don't know it's there", which he found similar to the game, in which "you have to find these little power-up things, and when you eat them you become the Altered Beast, this other creature that's really powerful and violent".

[7] The cover of the album, produced in five different colored versions (yellow, blue, green, orange and purple), features a dinosaur logo.

"[5] AllMusic agreed that the album is "all over the place", yet noted that "it takes a bit of time for all of it to make sense, but after a few listens, it falls together.

"[8] In 2018, independent vinyl reissue label Intervention Records announced that it would be releasing Artist-Approved 2 LP Expanded Editions of 100% Fun, Altered Beast, and Girlfriend.