Looks like PUBG Corp. really did push through in suing Epic Games for copyright infringement over PUBG. This is due to the fact that Fortnite might be replicating the experience that PUBG became known for.
The lawsuit was actually filed back in January in the Seoul Central District Court, according to a representative from PUBG Corp who told Korea Times. The case was against Epic Games Korea, a division of Epic Games in the said country. There were no specific claims in the lawsuit but according to PUBG Corp., they had concerns over Fortnite’s UI, gameplay, and “structural replication” as it had similarities with PUBG.
To further add to the rivalry, apparently PUBG Corp. and Epic had a business partnership where the PUBG developer licensed Epic’s Unreal Engine for the game. The lawsuit is currently limited only to Korea.
source: GameSpot