10-2

From SmashWiki, the Super Smash Bros. wiki

Non-playable 10-2
Universe	Super Smash Bros.
Appears in	Super Smash Bros. Melee
Availability	Not playable

10-2 is a stage in Super Smash Bros. Melee which can only be accessed through the use of an Action Replay device. Even so, the game crashes upon activation in Debug menu. Unlike similar non-playable levels in Melee such as DUMMY and IceTop, 10-2 is basically the same as IceTop and requires the same code as Icetop to access it. Judging from the name, it was likely an unfinished adventure mode level based on Ice Climber (10-1 is an Ice Climber level).