Secret Minigames (credit: markbart)
On Episode 8, Melissa Gale's stage, before reaching the Waiting Room (or after reuniting with Bella), go down into the basement and hide Bella in the incinerator using the "Hide" command. A cutscene will play and Bella will find a portable gaming handheld. This is archive item #32: JOYLiNK - Ultra Network King.
Now on the main menu, select "ARCHIVES" and view item #32. When you check out this archive, you will unlock the "MINI GAMES" option in the main menu.
Note that in order to be able to play these minigames, you must be logged into the PlayStation Network.