Thank you for the feedback, 
In reference too:
"After hovering some small icons in the tech tree to see detailed info the game was stuck. Music was playing, cursor was moving but I could not go back or close the tech tree or use ESC to bring up the menu. I had to terminate the game."
Would you kindly, submit a ticket via our support system so that I can better assist you with your issue. After following the link, run the support tool, include your steam name, describe the issue you are having and then send us the zip file to greatly speed up the process!
Link to forums for explanation:
https://forums.galciv3.com/452855/page/1/
Link to support tool:
http://sd.stardock.com/Support/supportToolTest/SDSupportTool.exe