Above, you'll see a snippet of the box art for Metal Slug: Double X -- one X short of ESRB problems. While the box touts a PlayStation Network logo, the game will only be compatible with the classic PSP-1000 through 3000 series. Why? An Atlus representative tells Joystiq that the publisher has no plans to release a downloadable version on the PlayStation Store; though a digital copy of 2007's Metal Slug Anthology (published by SNK) is currently available.

Launching February 23 exclusively on UMD, the upcoming 2D shooter, which is an updated version of Metal Slug 7 for DS, will feature seven levels, 70 mission-based challenges and an ad-hoc two-player multiplayer mode. With a $20 price tag, Metal Slug: Double X sounds like a deal. Too bad PSP Go owners, once again, will be unable to cash in.

This article was originally published on Joystiq.

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