Pirates who have downloaded one of the most popular torrent files of this week's big game release Watch Dogs - ironically, themed around computer hacking - have come in for an unpleasant surprise, reports gaming site Gamecrastinate.

The game, whose official release is May 26th, was pirated using various software, but one of the most popular “torrent” files – often used to pirate large files such as games – came with an unwelcome stowaway in the form of malware, according to Slashgear.

“Oh, the irony,” commented Slashgear’s Chris Davies on Twitter. Fans who had downloaded the SKIDROW version of the game found that a file entitled Winlogon.exe was consuming 25% of their computer’s power, reportedly mining the cryptocurrency Bitcoin for unknown criminals, according to Slashgear.

The irony comes from the fact that the game itself is themed around hacking. Maker Ubisoft warns gamers to “Prepare for a reality you may not be aware of,” and describes the game as allowing users to enter a world “where a hacker uses a hi-tech city as a weapon.”

Gamecrastinate, which originally reported the attack, said that thousands of users had been affected by downloading the pre-release torrent, and suffered effects such as blue-screen crashes, large power consumption and an unstable computer.

Gamecrastinate’s Peter Downey commented, “the latest trend in viruses is secret Bitcoin miners, and it seems that somebody jumped on the Watch Dogs hype-train to make some quick coin. Seems almost fitting considering the theme of the game, though the irony is probably not as entertaining if you’ve fallen victim to the hack.”

Geek.com describes the practice of adding malware to pre-release games as very common, saying “more often than not there’s malware attached.” The torrent affected is known as the SKIDROW torrent, and Geek.com describes its appearance in the hours before the game’s release as a “get rich quick scheme”.

The highly anticipated game is themed around a virtual city where players hack into victims’ smartphones and into the CCTV cameras that surround them,, according to Ubisoft.

Ubisoft has not commented on the adverse effects of the illegal torrent of the game.

“We are seeing tremendous excitement for the new Watch Dogs game,” said Michael van den Berg, vice president of Merchandising at GameStop International, in a pre-release statement. “In fact, Watch Dogs is the highest pre-ordered next-generation console game to date. It is on track to be one of the top selling video games across all consoles in 2014.”

The PC gaming community is well used to malware attacks, whether delivered as game "cheats" or as full games. A large number of pirate games carry some form of malware, and some reports have claimed that up to 90% of such “add-on” software carries malware.  Here are a few tips to avoid infection.