Fans of vintage arcade games know that the popular and free emulation tool MAME (stands for "Multiple Arcade Machine Emulator") can be used to recreate the experience of classic coin-op and console videogames on PCs, Macs and jailbroken iOS devices.
The catch, of course, is that in order to run the old games you need a copy of the game ROM code; said copies are essentially unavailable via legitimate licensing (except for a few Exidy games). The other catch is that full-scale emulators aren't particularly welcome on the iOS App Store; the ones that have made it through the review process are careful to lock down the ability to run arbitrary third-party programs.
That's why it was more than a little bit surprising to see iMAME show up in the App Store this week. The game emulator (which, if you judge it by its splash screen, seems to be a straight-up clone of the jailbreak-only iMAME4All app) plays the ten Exidy legit games as one would expect. The unsung trick, however, is that by using a file transfer tool like PhoneView or iExplorer, it's trivially easy to throw in additional ROMs and have iMAME spin them up. (I've been playing Track & Field for days and still haven't gotten past the long jump.)
It seemed too good to last, and sure enough it was. Running arbitrary emulated code is an App Store no-no, and as of 1:30pm today the iMAME app is no longer available in the US store. Sad news for everyone who ran out to buy a discounted iCade cabinet for the holiday.
Commenter Spencer points out that he & at least one other developer have built patched versions of the jailbreak-only iMAME4All project that will compile in Xcode and install on properly provisioned, un-jailbroken devices. This only applies, however, to active participants in Apple's $99/year iOS developer program; otherwise there's no way to install the patched app.