Sometimes they're the result of hackers and dataminers, other times they're caused by rogue employees or contractors, and occasionally they just happen by accident. Whatever the cause, leaks have seen screenshots, videos, and even playable versions of entire games bolt from the barn ahead of schedule. There's a mix of excitement, caution (spoilers!), and sometimes disappointment that comes with each surprise reveal—but they're all fun to reminisce about in hindsight, so here are some of the biggest leaks in PC gaming history. (No, it's not all Ubisoft games.)
A full month before its release date in 2011, a nearly complete build of Crysis 2, including multiplayer mode and online authentication keys, leaked onto a number of torrent sites. While it was buggy and contained a number of placeholder assets, it was still reportedly playable start-to-finish.
Lamentably, Crysis 2 went on to become the most pirated game of the year, and while it's suspected that the leak came from an employee of either Crytek or EA, the culprit has never been publicly identified.
The Witcher 3
The highly anticipated third entry into CD Projekt Red's The Witcher series was preceded by a massive info leak after the Google Drive contents of an employee was made public. Among the leaked files lay secrets about the RPG's story, enemies, quests, notes on "boob physics," and even the game's multiple endings.
The temptation to dive into the details of such an eagerly awaited game must have been enormous for fans, but we hope you managed to enjoy the surprises anyway. This wasn't The Witcher's first brush with leaks: several gameplay videos of The Witcher 2 were also spilled ahead of schedule.
Mass Effect 3
After an early build of Mass Effect 3 somehow leaked onto Xbox Live, dataminers dove into the code and resurfaced with a copy of the unfinished script. Lots of people had a look, a naturally lots of them then immediately began complaining about the contents.
Still, feedback is feedback. BioWare co-founder Ray Muzyka said they take fan feedback seriously, even if their fans are offering notes on a script they weren't supposed to see. Among the changes made to the final script may have been a few rewrites based on the notes they received on their leaked version.
In late 2002, over a year before its actual release, a demo of Doom 3 shown at that year's E3 was leaked onto the internet, allowing those who downloaded it to play the intro sequence and several early levels of the game.
According to a memo supposedly written by John Carmack (which, if real, was also leaked), the source of the leak was an employee at ATI, who was later fired as a result. None of that is confirmed, though, and whether the leak was accidental or deliberate isn't known.
Half-Life 2 and Counter-Strike: Source
Originally planned for September of 2003, we wouldn't see the release of the Half-Life sequel until a full 13 months later after Valve's network was cracked and the source code, maps, models, and playable builds of HL2 and Counter-Strike: Source were stolen and leaked.
The culprits were eventually arrested by German authorities after Gabe Newell pretended he was interested in hiring one of the hackers to work at Valve and obtained his contact information. The trial resulted in a two year probationary sentence for one of the hackers, and Half-Life 2 wasn't officially released until November of 2004.
StarCraft 2: Heart of the Swarm
The expansion for Blizzard's StarCraft 2: Wings of Liberty was released in March of 2013, but part of it arrived ahead of schedule. A video of the ending of the single-player campaign was leaked before the expansion itself landed. While it was a rough animatic, without lip-syncing and containing some placeholder storyboards, it was still a massive spoiler for the story.
While Blizzard wouldn't confirm it was genuine, lawyers quickly issued cease and desist letters to sites hosting the video, which is was a pretty strong indication the leak was the real deal.
Call of Duty: Modern Warfare 3
Back in May of 2011, Kotaku received a ton of information on the upcoming Call of Duty: Modern Warfare 3, roughly six months before it was scheduled for release and before it had even been officially announced. This info included details of the story, screenshots, and details about the game's weapons, levels, and modes, apparently from multiple sources within the developer and publisher.
In response, the developers had to accelerate their own marketing plan, and immediately released a number of trailers for the game.
We learned of the existence of Dishonored 2 in a rather embarrassing way: while rehearsing its first ever E3 press conference, Bethesda broadcast—live on Twitch, no less—a conversation between members of Arkane Studios (developer of Dishonored) that mentioned Harvey Smith (director of Dishonored).
After a few minutes of chatter someone finally realized it was going live over the internet and shut it down, but it was too late: a couple thousand fans had been listening the whole time.
World of Warcraft: Cataclysm
Before taking part in a closed alpha, participants are often required to agree not to share details of their experiences. What's harder is actually making sure they abide by that agreement, as with World of Warcraft: Cataclysm. Prior to the expansion's appearance at BlizzCon, one alpha tester posted huge amounts information about Cataclysm online, including screenshots and videos, details on character classes and races, dungeons, and other features.
The information was removed after Blizzard issued a takedown, reminding the player that 'NDA' stands for non-disclosure agreement and is, y'know, legally binding.
Stalker: Shadow of Chernobyl
In 2003, a pre-alpha for Stalker (which wouldn't even come out for another four years) was leaked onto P2P networks, and while it took some configuration to get working and was missing things like enemies and animals, it was still playable.
Ironically, the mod called Lost Alpha, which attempted to restore the game to its pre-release promise, was also leaked ahead of time by beta testers, forcing the modders to release their work early and ruining their plans for it to become an official paid expansion.
Assassin's Creed: Syndicate
Originally code-named Assassin's Creed: Victory, details about the next game in Ubisoft's AC series leaked well in advance. Assets included gameplay videos and the revelation that the game would take place in Victorian London.
Leaks are nothing new for Ubisoft, whose sprawling operation on several continents and scores of employees (ever watched the credits for a Ubi game?) apparently make it nigh-impossible to keep a lid on their business. Games like Watch Dogs 2, The Division, Far Cry Primal, and earlier games in the Assassin's Creed series have all had information leaked ahead of schedule. Maybe someday Ubisoft will actually batten down its hatches, but we're not holding our breath.