The marketplace system is to my mind excellent. 

Nevertheless, I see a few modifications that could be made to make it even better.


- If you manage to build " The Office of commercial/business validation " or something like that (I know only the french name) it would then be interesting to be able to forbid an or several empires to buy and sell in the market ! Like a blockade in a way, with avantages and disadventages if you decide to do so.

-  it could also be nice to be able to sell ressources every turn. I mean for exemple, I produce 100 titanium a turn and I want to sell 80 of it every turn so that I produce 20 titanium and x dust. This idea is from the fact that at the end of the game I often get 900 pieces of a luxury ressource a turn and its being sold automatically, without my having to type "999" and "ok" at each turn for each ressource would make the end of the game funnier.

- Seeing the price = f(time) luxury ressources graphic as having only white curves kills me. It doesn't give any useful information. Whether you give a color to every single luxury ressource or you find a way to make every curve belong to their ressources ^^

- It would be great to explain a bit better how taxes work, their influence, as I never know if I have to put it to 25% or if it is going to make buyers stop buying. 


Sorry for having put 4 ideas instead of one. I one idea specifically interests you, write it in the comments and I'll make it a standalone idea :)