Base: The Legend of Zelda: A Link to the Past · SNES · 2005 · Total Conversion
Creator: Euclid and Koh
A complete overhaul of A Link to the Past with an entirely new overworld, dungeons, story, and extreme difficulty, widely considered one of the most ambitious SNES ROM hacks ever made.
Parallel Worlds replaced the ALttP engine's content wholesale: new overworld maps for both Light and Dark World equivalents, 22 completely redesigned dungeons, a new story, new music arrangements, and a difficulty calibration aimed at expert players with deep knowledge of the base game's systems. The project took years to develop and was a technical achievement at the limits of what the ALttP engine permitted. Its reputation spread through the ROM hacking community as a landmark of ambition and craft, though its extreme difficulty made it accessible primarily to players already expert at ALttP. A revised version, Parallel Worlds Remodel, subsequently adjusted the difficulty curve while preserving the original design.