Do you think West Africa should at least be mentioned in the game? Spain and Portugal started to colonize Atlantic islands like the Canary Islands and the Azores in the 15th century. Prince Henry the Navigator patronized a lot of explorers, and it was largely due to his efforts that Portugal gained those valuable Atlantic colonies as well as Sao Tome. Batholomew Dias rounded the Cape of Good Hope in 1487, and Vasco da Gama sailed around the cape and even reached India by 1498.
Since European contact with the west coast of Africa largely consisted of trade, it probably shouldn't be on the map. The first real mainland African colony was in Angola, which is much further south than Senegal and Guinea. Maybe you can gain access to African trade (and just receive extra trade routes in the game) if you build enough advanced shipwrights.