Actually, Linux is more of a minority in the Gaming Scene than Mac, but yes Mac is right under Windows. It's because Micro$oft owns the market pretty much. They have for a long time. In fact, they also have bought most of the shares on Apple, so they pretty much own more than half of the company according to some articles I read on the internet - if that's even true. How much of the information on the internet can you without a shadow of a doubt trust is actually honest?
Anyway, as for the capes; apparently either the code or software within their game that show cloaks and the physics from them doesn't support Linux; Mac on the other hand is a little different, it is supported there. But Unix isn't drastically different from Linux so I don't understand why Mac and Linux are so far behind when it comes to what's available, besides maybe lack of money return on Linux; which is a shame for me considering I just really enjoy having all the freedom I get on Linux.
You shouldn't believe everything you read on the internet.