Well, not really a tax, more of one-off fee, but it's still causing no end of problems for South Korean indies. The problem is that the Korean government have decided to set up a ratings agency for games, and consequently all games published in South Korea under any format - and that includes slinging them up on the web - must now pay their own age rating (by the megabyte, illogically) or be classed as illegal naughtiness. Okay for the big corporates, but a nightmare for the indies who are trying to make it on their own, where a couple of hundred dollars is just too much, and frankly ludicrous for the amateur coders releasing stuff for free. There are few sources running with this story, but it seems to have emanated mainly from this post on Reddit, where the facts of the issue are defined for us in broken English. Meanwhile, TIGSource are debating what they can do about it over here. We presume it has knock-on effects for indies outside Korea, selling internationally over Steam and so forth, too. In fact, yes, here's a story on that. Thanks.
We will add our voices to those saying "Boo, that's not on. Give those guys a break, please, South Korean Government. Granted, you are a sovereign state and there's nothing we can really do, but some kind of consideration would be nice. Cheers then, bye!"