Stop 'n' Swop
When Banjo-Kazooie was first released in 1998, Rare intended to develop a mechanism whereby save data from Banjo-Kazooie could be shared with a future sequel, Banjo-Tooie, through a system known as "hot swapping." Players would remove the Banjo-Kazooie Game Pak, leaving the Nintendo 64 turned on, and then insert their Banjo-Tooie Game Pak. In theory, the Banjo-Kazooie save data would remain in memory and would be accessible to Banjo-Tooie. This feature, however, was scrapped, perhaps out of fears that using this method would damage the console and/or cartridges. Some remnants of Stop 'n' Swop are hidden inside the game's source code, although these features are inaccessible without using a cheat device. Allusions to the ill-fated Stop 'n' Swop have appeared in several of Rare's later games.
Stop 'n' Swop on MFGG
In February 2012, VinnyVideo wanted to develop a system for exchanging save data among games on MFGG. Hello soon responded with an example for developing a system for Game Maker games, and other MFGGers worked on a cross-platform solution that would work with both Game Maker and Multimedia Fusion games. Other MFGGers discussed the possibility of an elaborate collaboration involving many different games, where completing certain levels or achievements would unlock hidden levels or bosses in other games. Unfortunately, this plan hasn't come to fruition.
In November 2012, VinnyVideo released the first MFGG game with Stop 'n' Swop support, Darunia-Saria 2012. Since then, he's added SnS support to several other games, including Revenge of the Walrus, Aventura de Luigi, Daisy: Redneck Cowgirl, and Mario's Steroid Adventure. A future game, Cheerwine Deluxe 3, may tie these games together by adding assorted unlockables, but at present, CD3 is on hiatus.
Hello also created a form of Stop 'n' Swop called "The Exchange", which currently is included in Super Mario Bros: Ztar Turmoil, Super Mario Eclipse, Super Mario Dynamo, and Hello Fangaming Collection, and allows for in game collectables collected in one game to unlock content in a different game.
