Yo Tim, according to someone on a forum I linked to this post: >>>>> The link to Doukutsu (Cave Story) in there was for the Linux version. I was pleased to find out that there's also a Universal (non-Rosetta Intel) version available. Mac Download (universal) and the Mac Translation Patcher
but there sure is a great lack of indy games on the mac... well, actually a great lack of games generally, but one would think that the indy scene could be more prone to produce cross platform games or games for less widespread OSes like Mac OS and Linux
Anything open-source written in Java or SDL automatically is for Mac as well, no? It's a matter of compiling it on one, then playing it, but it's all there and as available as the open-source Unix games.