Sonic the Hedgehog Adventure Gamebook 4: The Zone Zapper

Sonic Adventure Gamebook 4: The Zone Zapper is a gamebook written by Nigel Gross and Jon Sutherland. It was published in 1994 by Puffin under the Fantail label. In it, Sonic must undo the results of Dr. Robotnik's new invention, a machine which turns good into evil and evil into good.

Overview
Is it a bird? Is it a plane? No, it's Robotnik.

It's not unusual for Robotnik to go round messing up the Green Hill Zone. This time, however, he's built a brand-new machine, which turns everything good into bad - even Tails! Sonic faces the fight of his life with his best friends. Will they survive and will he?

Think fast and act quickly - Sonic's going to need all the help he can get!