Minecraft wiki entry for 2010_Indie_of_the_Year_Awards, associated text: Minecraft can be modified by replacing or adding Java class files to minecraft.jar in Java Edition. This method of making custom modifications is not supported by Mojang as it can break the game if the mod is outdated, defective, or in conflict with another mod. Some such modifications impressed Notch or Jeb sufficiently that they were added to the game and the authors were credited under Additional Programming. Some examples of mods being implemented into the main game include Hippoplatimus' Piston Mod and horses from Dr. Zhark's Mo' Creatures mod were added in Beta 1.7 and 1.6.1 respectively.