UPDATE 13:35: Sadly it's now looking like this was a bit of an elaborate scam app, with several places reporting it is the some of the actual game but repackaged by a third party.
As of 14:25 It's now also been debunked by Studio MDHR themselves:
ORIGINAL STORY FOLLOWS: Well, this seems to have come out of nowhere. Xbox and PC indie hard-as-nails platformer Cuphead appears to have made a surprise release on the App Store, despite no previous mention the game would come to mobile devices.
The App Store listing on iTunes appears legit, with Studio MDHR named as the developer of the port as well as the support link, and the port appears to have it's own on-screen touch screen controls too judging on the screenshots on the listing. Sadly, it does look like co-op of the bigger versions is out, but it's available for iPhone and iPad for a very reasonable price of £4.99 at the time of writing.
There's been no word on any of Studio MDHR's social channels of this release yet, but we've got our fingers crossed this mobile version might come to Android and even possibly Nintendo Switch in the future too, even if it did result in adding some portable frustration to our collective commutes.
Cuphead is certainly out now on Xbox One and PC.