For those excited about the PlayStation 4's new emulator abilities allowing players to run PlayStation 2 games on the system, there is possibly a giant catch to how the system will work, and it might require gamers to buy new copies of games they already own.

Eurogamer reports that it seems that the PlayStation 4 PS2 emulator doesn't work with existing PS2 discs or PS2 game downloads purchased on the PS3. Gamers noticed this important detail after a tweet by BradazKing pointed out a game trailer for PS2 RPG game Dark Cloud running on the PS4.

That video, now pulled, included a statement in its description that "PS2 Classics and PS2-formatted discs are incompatible with the PS4 system." However, it did confirm features of the PS2 emulator, including 1080p rendering and support for remote play and share play.

Eurogamer was not able to verify the validity of the trailer, although screen shots of the video made it seem as if it were official. As of now, though, this is still unconfirmed information. However, if it proves true, it's likely to make many gamers unhappy, especially since it means that Sony will basically force them to spend more money on games they probably already own.

Of course, Sony would want to make sure that older games run correctly on the PS4, but competitor Microsoft doesn't have any such issues with allowing for backward compatibility: users who own certain Xbox 360 games can download versions of those games for free to play on the Xbox One, meaning this is a move that could put Sony behind Microsoft in pleasing players.

Sony announced the PS2 emulator on the PlayStation 4 just a few weeks ago, with the release of a Star Wars: Battlefront PlayStation 4 bundle that also included four PS2 games: Star Wars: Racer Revenge, Super Star Wars, Star Wars: Bounty Hunter and Star Wars: Jedi Starfighter. At the time, however, Sony stayed mum about the emulator's features and details.

"We are working on utilizing PS2 emulation technology to bring PS2 games forward to the current generation," wrote a Sony representative to Wired via email. "We have nothing further to comment at this point in time."

Eurogamer requested a comment from Sony on the issue, but hasn't yet received any new information from the company.