Once she returned to the white void at the start of the game, Andrea looked down and was surprised to see her naked body, realising she was still a girl! "Wha-what happened to me?" she asked, starting to freak out.
"Please stay calm," the voice said. "I should have explained. When you access a fantasy and take on a different form, back in the void you will keep that form until you take on another. This has no effect on your actual physical body, so don't worry."
"Okay," Andrea replied as she recalled the intense thoughts she'd had while in the fantasy. "So, uh, what was up with the fantasy about being turned into a girl and fucking a guy?"
"Oh, those are just innate desires," the voice explained. "Simulating an alternate body means the alternate mind will apply itself to the original one and make it adapt with transformative fantasies. In other words, it tells you you want to turn into this form to get you to enjoy it more."
"Ohh, OK!" Andrea was a bit relieved to find out that fantasy didn't mean she really had been suppressing wanting to be a girl her whole life. Looking at the fantasies, she saw a whole bunch where she was a girl now, as well as one of a guy jacking off that she guessed was alien to her girl mind but not to her boy mind.
After some consideration, she picked... (A/N: obviously feel free to add more!)