Banjo-Kazooie · Nintendo 64 · 1998
A cancelled cross-cartridge feature that hid mysterious eggs and an Ice Key in Banjo-Kazooie, intended to unlock secrets in the sequel Banjo-Tooie.
Rare designed Banjo-Kazooie to talk to its own future. Scattered through the game were tantalising, seemingly unreachable collectibles — six Mystery Eggs and a glowing Ice Key — that the studio intended players to carry forward into the sequel by physically swapping cartridges while the N64 was still powered on, exploiting the way the console’s RAM held data for a moment after a game was pulled. Late in 1999 Nintendo warned that revisions to the N64 hardware would shrink the swap window to about a second and risk damaging consoles, and the feature was scrapped before Banjo-Tooie shipped. Rare left teasing clues in place — after 100% completion Mumbo Jumbo reveals the locations of hidden eggs and the Ice Key — turning an abandoned mechanic into one of gaming’s most enduring mysteries, obsessively datamined for years before the Xbox Live Arcade ports finally made it work.
Collect all 100 Jiggies; after the ending, Mumbo Jumbo shows animated photos revealing the hidden locations of two Mystery Eggs and the Ice Key in areas previously glimpsed but unreachable.