This minor update allows you to add more Civilizations to your game in single player by adjusting the Map Size (NOTE that this option will not actually change the map's size; just the number of Civilizations).
Duel: 2 players
Tiny: 4 players
Small: 6 players
Standard: 8 players (This map's actual size)
Large: 10 players
Huge: 12 players
In multiplayer, the map tops out at 8 Civilizations (as is the maximum number of players allowed in a multiplayer game of Civ 6). The map should always contain 18 City-States, no matter the map size. I admit this is a strange methodology, but at least you can play with 12 Civilizations in single player instead of just 8.
In the next update I'll try to have all Civilizations playable in a single game. Also I'll see if I can get a couple of more Great Prophets available for more religions, and more amenities per luxury resource and buildings so I can scale back on the resources a bit (more room to build districts and wonders). Most of all, I hope to get the Natural Wonders to work. All these updates may take me a little while figure out, so expect some time to pass before the next major update.
Thanks and enjoy.
Paul's Standard Earth Alpha v1.2.2
Standard Sized Earth Map with Roughly True Start Locations