Minecraft snapshots can 'destroy your save games'
In light of the gaining popularity of Minecraft's weekly snapshots, and the increasing number of angry emails received, Mojang has issued a warning to all PC players.
"The snapshots can potentially destroy your save games," lead developer Jens Bergensten warned.
Despite what some Minecraft players want to believe, the snapshots are not 100% guaranteed to work. While Mojang tries to ensure a working snapshot, the point of them are to "give previews of possibly broken features."
"Expert users could satisfy their curiosity, and we received invaluable feedback on work in progress," Jens explained on how the weekly snapshot was born.
If you plan on downloading the weekly Minecraft snapshot, do so at your own risk.
"Only use them if you know what you are doing," Jens stated. "To “install” a snapshot, you download the JAR file and replace the one located in your “application data” folder. The easiest way to find that folder is to start the game, select “texture packs” and click on the “open texture pack folder” button. It will locate “.minecraft/texturepacks”, and the JAR file should be placed in “.minecraft/bin”."
"To UNINSTALL the snapshot, start the launcher (Minecraft.exe on Windows) and click the “options” button. Then click on “force update” and login as usual. The launcher will then download the official JAR file for you. Note that save games created in the snapshot may not work (and probably doesn’t) in the official version of the game."
If you prefer a safer alternative, you can wait until Mojang releases an official, well-tested update that fully contains all of the previously released content seen in the snapshots.
Meanwhile, if you enjoy the risk of seeing new features early you can see the list of changes introduced in today's Snapshot 12w22a here.