Is there any option whatsoever for Unity to use future versions of Mono, or does the GPL corruption in more recent versions mean that they're legally stuck with an outdated version?
Unity has a license from Novell for an older version of the software, which is how they can use it in places they can't use the LGPL. Xamarin sells Mono under a commercial license, but Unity apparently doesn't want to pay what Xamarin is asking for a license to the updated code.
Which is sad because the massive unity code base is stuck in the C# dark ages.
On the other hand, mono is 'open source' so it's kind of rubbish for Xamarin to be asking license fees when they have their own (pretty rubbish) competing game stack with monogame that they have a vested interest in (not commercially, but Xamarin developers work on it).
I find this sort of 'kind of open source but actually you have to pay us ahahahahaa~' thing pretty distasteful.
Unity is free to use Mono commercially under the existing open source license, so long as they contribute their changes to the Mono runtime. They can even take advantage of this without making any of their own code open source, because Mono is licensed under the LGPL, not the GPL itself. Xamarin has made it very friendly to use Mono in commercial products without getting paid for it. I don't see what's distasteful in asking people to pay if they want license terms that go above and beyond what the LGPL offers. The commercial party gets the additional licensing features they want, and the money funds further development effort which goes to other users of Mono, both paid and libris/gratis users under the LGPL. Everybody wins.
Mono's licensing decision actually makes sense now; hampering the free version of Mono with the contagious GPL license effectively means that you're required to pay if you want to use their software in a commercial fashion.
Very disappointing that Unity haven't upgraded yet, hopefully they'll do so soon.
That's not true. The LGPL explicitly allows closed-source programs to incorporate it (that's why it's the LGPL and not the GPL). The problem is that the LGPL is incompatible with certain use cases (embedded systems, I think the App Store, possibly the various consoles) so Unity can't distribute LGPL code to those platforms.
Does LGPL require just the release of source code for games infected with it, or do developers have to release their assets also (like art, sound, level designs, anything needed for the code to be meaningful)?
If the assets aren't covered, I think Unity could go LGPL in some way.
It's the 'I want a piece of your pie' thing, that I also find troubling with patents.
Person A: Invents something, fails to capitalize on it.
Person B: does marketing work, sells all the Monies!
Person A: -__- Oh that was clever. Actually, I want some of your money please.
Person B: Fuck off. <--- The correct response.
If you make something and want to sell it, sell it. If you make something and give it away for free, don't come crying when someone else sells it.
The 'dual license GPL' approach to software which is 'kind of free unless you sell it, in which case we'll negotiate some nice on going licensing fees' seems disingenuous to the spirit of open source (and specifically the GPL) to me.
You clearly don't understand open source. Go do some reading and later come back here.
Some tips: free doesn't mean "gratis", it comes from "freedom". Therefore it is normal that the GPL uses a strategy to avoid that derived works become proprietary ('proprietary' means: essentially "non-free" for the end-user, and "free" for the developer).
From your comment it seems that you confuse the fact that opensource is not something that benefits the developer; it is something that benefits the end user! Don't forget that.
Nowadays if I needed scripting lang I would probably go with Dartlang: better license, not a clone, probably better perf, simple concurrent prog model and still syntax is familiar.
