While part of me is happy to see the MMORPG genre take what will almost certainly be a huge and vicious hit (still some lingering spite towards it, long story)... I have to say this is actually a bit worrying. Not so much for what would happen to the MMORPG genre (somewhat want to see it crash & burn, though I didn't expect to see something which could legitimately cause that), but because it seems to be the government is overstepping its bounds a bit; the results could easily be overkill and have a lot unintended consequences.
Be careful what you wish for?
It might be due to the lack of information right now, but this could be (entirely?) a good thing if the details were laid out in a way to keep the effects of the proposed law in check. It'd involve quite a bit of careful work with the fine print, but it can be done. Nevertheless, it's still touchy territory for a government to be taking such a direct role in the matter; at least they're going after a genuine issue with games rather than a frivolous one (censorship and the what-not).
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As for it not directly affecting nations other than South Korea?
Think about the long-term effects of this type of bill passing for a minute.
While other nations might not have that type of proposal on the table right now, how long will it be before those proposals are actually on the table? This is part of the reason I said it was worrying, other nations could easily start doing the same if it passes. It might not be a problem now, but it may be a problem later. This could be after the seeing what the effects of the law (if it passes) in South Korea, and that may be what determines whether or not others will consider doing the same.
Again, it could be a good thing... but with the already less-than-favourable reputation gaming has right now, there's no guarantee that the politicians are going to handle it properly. The South Korean government seems to know where some of the actual problems are, but it's not quite the case on this side of the Pacific; it's here where you're more likely to see the bill proposal which will cause more collateral damage due to a less carefully laid out proposal. Yes, there will no doubt be gaming lobbyists which would try to go against it; but there still will other lobbyists which will push for it to pass as well.
Just don't think it won't affect you because it's in another country; and that's simply because awareness of this can give another politician, one closer to home, ideas.