Factorio RNG Reverse-Engineered to Predict Legendary Item Crafting
Factorio's official documentation frames quality as a matter of statistics in mass production, and this work shows the underlying generator can be solved from inside the game's own circuits, turning a resource grind into a scheduling problem.
Reporting from 1 source: GIGAZINE.
A computer science graduate student has reverse-engineered the pseudo-random number generator behind Factorio's quality mechanic. Based on a 2014 tip from a former developer, he confirmed the game uses taus88, three combined linear feedback shift registers. By recycling repair packs in Factorio 2.0, he observed 88 bits of output over 44 operations, reconstructed the generator's internal state, and used in-game circuits to predict future quality rolls. He also automated skipping unfavorable random numbers to reach Legendary results.
The quality mechanic in Factorio: Space Age assigns five tiers to manufactured items: Normal, Uncommon, Rare, Epic, and Legendary. Quality modules give each craft a chance to produce a higher tier, sometimes jumping several tiers at once, and the documentation treats the outcome of large production runs as a statistical matter.
The random numbers behind those rolls come from a pseudo-random number generator, and the analysis identifies it as taus88, built from three linear feedback shift registers. Because an LFSR's internal state can be back-calculated from enough observed output, the state is recoverable. Recycling repair packs yields two bits per operation, so 44 recycling operations provide the 88 bits needed to rebuild a working state.
Synthesized by Yomimono from the 1 cited source below, including Japanese-language reporting where cited, then editorially reviewed before publishing.