1 change the names, i can understand land, navy, production techs but what is trade tech? europe conquer the world by land and navy tech, but they control the market not because the tech, but the practice and will (and guns to open the market plus new trade goods and gold from the America). So just change the trade tech name to trade practice may sounds a lot better. Same as the government tech, what's that? Should be called political practice or something like that.
2 different slow down effect for different tech, not a universal tech group efficiency. e.g. Europe has much faster pace in land and navy tech than china, however, i don't see the reason for a same fast production tech speed. In the end of the day, the production tech in Europe shows advantage only after the industry revolution or at least after Newton.
3 Dynamic research efficiency, it's actually a supplement for the above point: lacking wars or signicicant rival will slow down the land tech, lacking knowledge about the world will slow down the navy tech (the close you are, the closer you will be, until someone knocks on your door!), lacking scientific method will slow down the production tech later (we can force Galileo and Newton born in Europe to show the Latin tech group advantage), too stable for too long or lacking neighbours will slow down government one, lacking trade will slow down trade (same reason for navy)
4 Maybe also allow go back in tech by events to model certain historical event...
2 different slow down effect for different tech, not a universal tech group efficiency. e.g. Europe has much faster pace in land and navy tech than china, however, i don't see the reason for a same fast production tech speed. In the end of the day, the production tech in Europe shows advantage only after the industry revolution or at least after Newton.
3 Dynamic research efficiency, it's actually a supplement for the above point: lacking wars or signicicant rival will slow down the land tech, lacking knowledge about the world will slow down the navy tech (the close you are, the closer you will be, until someone knocks on your door!), lacking scientific method will slow down the production tech later (we can force Galileo and Newton born in Europe to show the Latin tech group advantage), too stable for too long or lacking neighbours will slow down government one, lacking trade will slow down trade (same reason for navy)
4 Maybe also allow go back in tech by events to model certain historical event...