Recently the game has been given great feature by 
It is almost unbelievable, that in Ogame they didn't make something similar to this solution and still after almost 20 years you have to trust your trader or you may be tricked.
I can see a great potential in improving this feature.
This idea came up with 
So you will be able to select with who you want to trade. Restriction can be made for friends, allies, trade partners, everyone without enemies. That will make the game more complex and strategic, since you will have to choose wisely who is your ally and who is your enemy. This will not corrupt current offers which can be made for all.
My additional idea is that you could make special offer with different prices. In example, placing order what for player X cost 400 000 Metal, but for your friends it is only 350 000 Metal. Buyer will be able to see that this is unique price, the last price will be crossed and the new one will be visible. Or there will be new price but with additional note "-12.5%", "-50 000".
It can be done in form of checkboxes and textfields, easy to learn and gives big opportunities.
For an example, first click button add special offer then fill checkboxes for who is it, and place different price. Also it will be good to add more than one special offer. Algorithm will have to check what is the best offer for specific buyer: "-12.5% for friends", "-10% for trade partners", so for a friend in different association with trade agreement it will show "-10%".
Sorting columns by resource gained by trade, price, time to destination and delivery time. This small improvements will be necessary in the future when marketplace will be crowded. Also adding column with parameter "ratio" can be very positive.
Filtration is second thing needed in full marketplace. Making bids visible only if they fulfill requirements. Maybe the other side would not like to trade with enemies. Or would like to select from offers that will be completed in specific time. Selecting searched resource (metal, crystal, deuterium) for another defined.
This features should work parallel and fields in filtration should be easily edited.
Humans in general are visuals. Small improvement which brings color to marketplace and highlight who is who.
For an example, red - foe, green - ally, blue - friend, purple - business partner, etc. Maybe adding small legend as it is in galaxy view.
Maybe you see an interesting offer, but you think it can be better? What if you could negotiate price without the need to return fleet and placing another offer? I suggest that, you could send a special message, which will be linked to specific order on market. Buyer will be able to propose new price and to complete the trade, seller should accept it or ignore it.
Small upgrade from what is now. Currently, when you buy something, you get only:
"Your fleet is flying to x:y:z with A Metal, B Kryształ, C Deuterium and it costs D Deuterium"
I would like to know what I will get in return, who is on the other side and when the fleets will be at place (Besides the fact I can reed it from fleet panel). I am not sure what gets bidder, but maybe we can correct it too?
The confirmation button of accepting the offer is needed to to avoid mistakes. This has to display in other place than "buy now" to elude double click and be easily noticed, e.g. in the center of the screen. In addition to the button "accept" and "cancel" should be displayed information summary of the offer.
Part of ideas presented:
https://steemit.com/steemnova/@steemnova/steemnova-ogame-based-browsergame-for-steemians
https://steemit.com/steemnova/@dotevo/community-steemnova-spy-probes
