A listing for an Xbox One release of free-to-play cooperative third-person shooter Warframe has appeared on the European ratings agency PEGI's website.

Rated PEGI 18 and reading identical to the game's other versions, the agency's website describes the Xbox One edition as containing "Extreme violence" and that the "content of this game is suitable for persons aged 18 years and over only."

Initially announced for Windows PC in early 2012 and entering open beta beginning early 2013, the Digital Extremes-developed title is currently available for Windows PC and Steam. Warframe is also available on PlayStation 4, launching alongside the console in November, joining other free-to-play titles such as DC Universe Online and Blacklight Retribution.

Microsoft Studios corporate vice president Phil Spencer told Polygon last month that the company will eventually embrace free-to-play titles for the Xbox One.

"On Xbox 360 we've got a number of free-to-play games," Spencer said, "and we're learning about what the console space is like for free-to-play, because it's different than PC or mobile. You have to think specifically about the audience you have on console, what they expect. But the learning that we're doing on 360 with the partners we have on free-to-play is definitely something I look forward to bringing to Xbox One."

Warframe for the Xbox One is not listed on the North American Entertainment Software Rating Board's website.