I am close to starting development on a large strategy game in which you can move units across a large playing area, that resembles game play of games like Civilization 5. Are there any good engines for this kind of mechanic out there or would I have to write the engine from scratch?
If you are just going to use SFML I would just build your own framework for the game using SFML and maybe Thor. Might take you a bit longer but would be worth it in my opinion. If you run into any problems or need help with a certain aspect of the framework just post here and I am sure someone can help out with it. I can also supply you with some sample code from my framework I am working with if you need a starting point, or idea for a certain aspect.