Lots of custom nations that you can play as.
Lost Viking Colony of Vinland
Based in the 3 provinces of Newfoundland, this is a Norse (religion and culture) colony that settled in North America long ago, it lost contact with the Old World and over the following decades struggled to survive. Now its become a stable duchy and is ready to start expanding into Canada and the American Northeast. Ideas are focused on colonization, land and naval warfare, and religious conversion. It can be a bit stale the first 5-10 years where you are just colonizing and don’t have much gold to spare, but once you reach the tribes the fun starts. They have usually formed some large alliances that can be hard to beat. Eventually the europeans will arrive and if you aren’t strong enough, you will lose.
Merchant City of Canton
This micro nation is based on the 2 Chinese cities of Canton and Macao. In the playthrough you will become a tributary of Ming and is in most ways still a part of China, but with some resourcefulness and willpower you can avoid being eaten and start colonizing and conquering the tribes of the Philippines, Indonesia, Australia, and eventually become strong enough to become free from China and start taking more rich ports from them. I take the merchant republic, and use colonization, trade, economic and naval warfare ideas.
Zambia Warrior Tribe
Take the 7 uncolonized provinces between Congo and East Africa, from Lenje to Rukwa. Then make a tribe overloaded with military and admin ideas for maximum warfare. Because of your position, you can go west, east and north easily. This custom nation is some of the most fun straight up warfare you can have in the game. In the start you will face off against strong alliances west and east, so you have to be clever and find the best opportunity to strike. After you’ve beaten your neighbors you can go northwest towards the gold provinces of Mali or northeast towards Ethiopia. I add a colonist to get the uncolonized african provinces, but you can also use it to kickstart a colonial empire.