I took a stab at a project recently in translating over Crawl's excellent tileset over to ToMe. I think Shockbolt is great from an illustration standpoint, but horrible for utilitarian purposes because the art is not uniform or clear enough to facilitate easy distinction and the absurd amount of detail muddies the look from a distance.
I downloaded the latest Crawl source (found here) since it contains individual sprite files for each enemy, dungeon feature, playerdoll, etc. The process was usually as simple as finding the appropriate corresponding file and renaming it. Because ToMe has a great deal more enemies (too many needless variations in my opinion) I had to mess with hue/saturation on Paint.net to get distinguishing color schemes. The playerdoll system is what I found most fun, since I got to play dress up with the individual components in order to build sprites for the unique characters in ToMe. Still, it would be preferable to have more "dynamic" sprites (see the dwarves below) but that's beyond my skillset.
That said, most of the work is quite tedious since you're just renaming files for the most part. I also couldn't really figure out how to change the terrain and gave up shortly after.
Here's a sample of what I was able to do:
Is there any interest in this? I definitely won't finish this on my own since I have life obligations and the like but was wondering if there are people willing to assist.
Not that I can help you with it - got my hands full.