With the recent announcements, I have decided to make the Wattage Tile Engine open source. I hope this can benefit the community in some way. It is a fast engine that supports dynamic lighting, line of site, and changing tiles on the fly. The full feature list can be found in the documentation.
The source code can be found here.
A lot of effort was put into the documentation to make it as clear as possible. It contains complete API docs as well as a quick start and around a dozen sample projects to show different features. Check out the documentation.