Open Source Turn-Based Strategy Game Engine?

Question

Is anyone aware of a turn-based based strategy game engine that is open source?

Answer 1

FreeCiv is FOSS. I don't what engine it uses, or whether it is usable outside the game, but since it's open-source, you can always have a look inside.

Answer 2

There is a list of open source turn based strategy games located here
They are all written in Ruby and some use rails.