I just got news that Velvet Assassin has been ported over to the Mac and is available on the App Store! However, I was not at all involved in the Mac port and I don’t know the developers who did – it came as a surprise to me as to anyone else in the former team. Here is a direct iTunes link: (Edit, no longer available as of 2021, unfortunately).
Shader Bug on ATI graphic cards
Unfortunately there is a shader bug with ATI graphics chips. It happened to me while trying it out on a 2011 iMac with an ATI Radeon HD 5670. I got reports from friends that this is not a problem of the Mac port itself but it happens on PC too. The problem is related to ATI chips with drivers that are newer than 2010 or so. Here is a screenshot: