These are things ive posted weeks ago in other marco threads:
I think he could be a great feature if done right.
For starters he shouldnt be a weekend only feature.
2nd he should always allow you to trade 3 ntg for 2 of another ntg
3. he should give us another use for diamonds, not sure exactly how though. Maybe something like speed ups. So for 16 diamonds you can buy a 3 hour speed up to apply to a building or research. Limit to 1 purchase per day. I think this feature more than anything would make the player base very happy.
4. he should allow us to trade 2:1 gold:food
There are many other good ways they could use him but i think the above is a great start.
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To avoid the NTG issue, we can treat marco like the Card Shop in Clash Royale. The offers change every day with exception of the 3:2 ntg and 2:1 food and the diamond trade.
I see the 2:1 gold:food trade to be more of a, man im 300k short on gold for this upgrade, my troops are going to take 35 min to train and i have to go, so ill take my excess food and trade it for gold so i can start the upgrade.
If you are grinding walls, there is no reason to make a food/gold exchange.
I was even thinking about the potential of something like 10,000:1 food/gold
il.
Im just getting into IA a bit more deeply and realize how much oil everything is going to take. It took me about 5 hours today to grind 43k oil so i could upgrade my castle with the discount we get right now.
I think something along the lines i have stated would go a long way into making the player base happy. First i want them to fix sandbagging and some of the huge bugs in the game, then look into this idea.