RubyDung inspired Notch to make Minecraft when he wanted RubyDung to have a first-person view, but when he tried making this, he thought that the textures were too blurry and distorted. Shortly after Notch's days coding for RubyDung, he came across the game Infiniminer, which put down the foundations for Minecraft.
On October 30, 2009, Notch talked about RubyDung on his blog in an entry titled "The Origins of Minecraft".
The name "RubyDung" was a placeholder name for a dungeon game in the "rubylands", a rough draft of a game world by Notch.
Creation of Minecraft
Notch's inspiration for Minecraft came after he played Infiniminer. Some time later, Notch created Minecraft.
Minecraft's source code came from RubyDung, so early Pre-classic versions of Minecraft have the "rd" (RubyDung) prefix. Early Minecraft versions were based on a combination of Infiniminer, Dungeon Keeper and the source code of RubyDung.