Hi Ginseng
First off, that looks like a really interesting project
Stonesense is an open source project, and is so the collaborative
effort of a handful of programmers and artists.
As anyone is free to contribute to - and use Stonesense, we feel it
fair to allow other projects the use of our code and graphics.
There are, however, some restrictions we ask that you observe if you
wish to use the Stonesene artwork:
1) Credit the source. The artists put a lot of work into the sprites,
and so we simply ask that Stonesense is credited when the artwork is
used.
2) We ask that the sprites are not used in any commercial or for-
profit implementation of any kind. This means (but it not limited to)
you can not sell anything containing the sprites, nor use them on site
running ads. Basically, you can not charge anyone for them.
But of course, once your project gets to that stage you might want to
invest in your own graphics. Freelance pixelart artists are fairly
reasonable to hire.
And lastly, please do not redistribute the sprites to a 3rd developer,
rather just point them our way and I'll take care of it :)
Hope this answers your questions!
Good luck with your project :)
- Jonas Ask