When originally making the update around two years ago, it was going to introduce this character for the hard mode of the game. It's name was Insanity, a brown, square-headed robot that basically acted like a mix of Crazy/Cartitan and Endy. Starting from a back room in CAM 1, it would make its way down Crazy's path and its eye would either change to an alarm shape or an eyeball shape, letting the player know what to do to fend it off.

(First picture is a remodel I did about a year ago, second is a screenshot from gameplay)

In fact, Crazy Fun Fact #4.5: Next Game was originally planned to be Insanity's theme song, playing at around 2-3 AM when it was active). Insanity wasn't used because it had this really complicated lore reason for existing and I thought the update would be better as how it is now)

(Thanks to @NatzTheRatz for this Insanity fanart she made 2 years ago)