I actually kind of like the blue myself, because it can give the impression that the cave is really, really large.  It would probably be better to have some background detail tiles to go with the blue area (stalactites, stalagmites, etc).  I tried making a blue version of the current background tile, but it didn't really work.  For the cave to have the appearance of being really large, I think it'll need some special tiles meant to give that impression.

I know at least some browsers have a way to do that, which is why having a built-in zoom on the site would be good.  There's no way to turn off that filtering when you view the image on its own (as far as I know, anyway).

@Mumu: I really like those random elements.  I'm going to use some of those ideas. :)

A lot of this stuff has come up in the past and been discussed extensively, so I'm going to briefly explain OGA's positions on it:

Artwork submitters on the site may also benefit from a license which allows all of the freedoms of CC BY 3.0 for non commercial games but if used in a commercial game, the artwork would automatically revert to a commercial license as specified by the copyright holder.

This is the same as an NC license.  There is simply no way of doing this in a way that is compatiable with open source and free software.  Furthermore, before OGA, there was a huge glut of NC-only art all over the web that was impossible fo use for serious projects.  That art is still out there and available, but putting NC-only artwork on OGA would dilute overall userfulness of the archive (right now, every single piece of art here is available for use in open source software, and a significant portion of it can be used commercially).  NC-only art is really only usable for hobby projects.  It severely limits what you can actually do with it, how you can distribute your games, etc.

Note that OGA has nothing against NC licenses; they're just outside the scope of the site.  I really don't like to shut discussions down, but this particular one has been rehashed a lot, and there just isn't any room to negotiate on it.

I think of most value would be a version of the CC BY SA license which explicity requires direct modifications of the artwork to be redistributed under the same license but doesnt require the entire game or other artwork to be licensed the same way. Currently, its very difficult to make use of any CC BY SA licensed art because its unclear whether it can be used in combination with commercially licensed artwork.

You might be onto something with this -- that is, some sort of weaker share-alike requirement that allows people to combine the works with non-sharealike works.  However, for a license like this to work, it would need some clear criteria about when the sharealike clause would be in effect and when it wouldn't.  The criteria would need to be strong enough to keep someone from including a tiny portion of another piece of art just to break the license, but not so strong as to discourage legitimate use.  I'm open to suggestions.

That said, in all honesty, the thing about licenses is that there are already way too many of them.  I've had my own ideas for licenses, and I'm hesitant to put them into practice because the fact that a piece of art uses a new license means that license needs to be reviewed and approved by legal experts.  That in itself would limit the usefulness of art content.  While there are some ambiguities in the licenses we already have, there are certain well-defined areas where people know that they can be used.  Introducing a new license would set things back by forcing people to go through the vetting process again.  As such, I would be very hesitant to do so unless there's strong demand for it.