RubyDung was an unreleased base-building strategy game prototype created by Markus “Notch” Persson. Developed prior to Minecraft, the project was inspired by Dwarf Fortress, but with a focus on accessibility. The name "RubyDung" was a placeholder name for a "DUNGeon game in the RUBYlands", the "Rubylands" being a rough idea for a game world that Notch had. During the later stages of RubyDung’s development, Persson discovered the indie multiplayer game Infiniminer, developed by Zachtronics. This inspired him to experiment with a fantasy-themed, first-person, block-based prototype, reusing and adapting portions of RubyDung’s code and assets. That experimental prototype demonstrated strong performance and positive early reception, leading Persson to abandon RubyDung entirely and pursue the new project full-time. This work would eventually become Minecraft, with RubyDung serving as a direct technical and conceptual predecessor.