:D
I would love to someday make a sequel that scales from Prehistoric Era to a Future Era ! But as for Spin 2, it will be much more modest. The reason is to keep the size of the project manageable for a single programmer, and to test new ideas. A small game delivered is better than a big game unfinished.
Also, considering the immense number of civilizations that could be featured, Spin 2 will probably only feature new ones, for the sake of variety. So Egypt, possible, but Palawa, unlikely.
I enjoyed making this game, so I'll probably do Spin 2 eventually, but I'm currently working on another game in order to raise funds for Spin 2. If you know other people who might enjoy Spin-vilization, you can help by telling them about it. You can also directly advance the project by donating. And anyway, thanks for your words of support :)