Dying Light has a special surprise for anyone who plays the open-world zombie game tomorrow, April 1, which is April Fools' Day. "Something unusual is going to happen in the world of Dying Light tomorrow that will radically change the game experience for one day only," developer Techland said.

A new batch of Antizin--the Dying Light in-game virus cure--has been "exposed to a foreign contaminant," Techland said in a statement. As a result, all players who pick up a supply drop containing the non-toxic chemical will experience a range of side-effects.

According to the video above, these side-effects include super-human strength, among other things. The side-effects are listed below; check out the video above to see them in action.

Uncontrollable fits of physical violence

Excessive strength and agression

Persistent muscle tension

Severely altered motor skills

Obsessive compulsive need to kick stuff

“All undelivered Antizin crates have been destroyed, and we would like to assure the survivors that untainted drops will resume as of April 2nd," Dying Light's fictional Global Relief Effort spokesperson Hudson Jenkins said. "We urge all the survivors to use extreme care when exhibiting symptoms of the contaminated Antizin injections."

Dying Light launched in January and is selling well, outpacing the mark of its predecessor, Dead Island. The game sold more than 3.2 million copies during its first 45 days on sale.

Following Dying Light's debut, Techland has launched a variety of free content and more, including additional weapons and outfits, as well as a Hard Mode. Going forward, Techland plans to release mod tools for the PC edition of Dying Light. The studio also pledged to actively support all versions of the game with more maps, modes, skills, quests, and "other original content" in the future.

For more on Dying Light, check out GameSpot's review.