Map Scarce Resource Challenges

I don't know if this has been suggested before, but maybe have extreme resource scarcity. Give players enough to get started, but they'll quickly run out of iron ore, copper, etc. They have to use contracts or map locations to make up the difference. So they have to use what they do have wisely.
Or have certain resources scarce. For example, one map could have a huge supply of oil, but all other resources scarce. So the player would have to quickly develop their refineries to trade for others.