For years, Maciej "Groobo" Maselewski was celebrated as the undisputed champion of Diablo speedrunning. His remarkable 3-minute, 12-second Sorcerer run seemed unbeatable, aided by powerful glitch exploits and seemingly unbelievable luck in Diablo's randomly generated dungeons.
Initially, Groobo's record-breaking run was accepted as legitimate, but a dedicated team of speedrunners began to question its authenticity. By utilizing outside software and analysis tools, they attempted to replicate Groobo's unbelievable luck and found themselves unable to do so. This led them to conduct an automated search through billions of legitimate Diablo dungeons, only to find that Groobo's run could not have occurred in any of them.
"We just had a lot of curiosity and resentment that drove us to dig even deeper," said team member Staphen to Ars Technica. "Betrayal might be another way to describe it," added team member AJenbo. The discovery that Groobo's achievement was illegitimate sparked a sense of betrayal among the community.
If you are familiar with Diablo speedrunning, Groobo's run seems akin to winning the lottery. The dungeon he navigated featured staircases conveniently placed near each other, providing a quick, enemy-free path to lower levels. Additionally, Groobo's fortuitous discovery of Naj's Puzzler on level 9 enabled teleportation crucial for late-game maneuvers.
"It seemed very unusual that we would have so many levels with the upstairs and the downstairs right next to each other," explained Allan "DwangoAC" Cecil at a recent presentation. The team sought to replicate Groobo's fortunate circumstances.
Beginning in February, a team of tool-assisted speedrunners (TAS) embarked on a search to find an RNG seed that could replicate Groobo's run. Using a custom-built map generation tool, they reverse-engineered a disassembled Diablo executable. This tool allowed them to analyze the billions of possible random seeds for optimal speedrunning conditions.
"We were working on finding the best seed for our TAS, and also trying to identify the seed from Groobo's run," said Stephan. Despite their efforts, the team struggled to find Groobo's seed because it simply didn't exist.
The TAS team conducted a distributed search across 2.2 billion valid RNG seeds, corresponding to different specific seconds on the system clock when a Diablo save file is created. Despite exhaustive efforts, they could not find a single dungeon containing the crucial level 9 Naj's Puzzler drop, leading them to explore impossible seeds created by save modification tools.
Eventually, the team discovered dungeons matching Groobo's video using seeds associated with the years 2056 and 2074. This revelation demonstrated that Groobo's run was manipulated, as legitimate runs could not produce such results.
As the investigation continued, more inconsistencies in Groobo's run surfaced. For instance, the 1996–2001 copyright date on the title screen was inconsistent with the v1.00 on the initial menu screen, suggesting spliced footage from multiple game versions. Additionally, items acquired early in the run mysteriously vanished from the inventory.
Groobo's final fight against Diablo also raised questions. Although technically possible, the speed and damage output during the fight only matched when using a level 26 Sorcerer, not the level 12 Sorcerer depicted in the footage.
After the TAS team presented their findings, Groobo defended his submission by stating, "My run is a segmented/spliced run... it was never passed off as anything else." However, Speed Demos Archive (SDA) determined that Groobo's run likely involved illegitimate techniques, leading to its banishment.
Despite the controversy, Guinness World Records still lists Groobo's record as the "Fastest completion of an RPG video game." This ongoing recognition remains despite the compelling evidence presented by the TAS team.
The incident had a significant impact on the Diablo speedrunning community. "Groobo's alleged cheating in 2009 completely stopped interest in speedrunning this category of Diablo," said Cecil. For over a decade, the community was discouraged from attempting this category. With Groobo's run discredited, new runners are setting records using confirmed legitimate RNG seeds.
Cecil hopes that the evidence surrounding Groobo's run will encourage scrutiny of other record submissions, reminding the community to question even the most familiar and respected figures.
