Yes, an other map would be required for the Space Age. Some kind of Archipelago with planets of different sizes. An then you have to do some island hopping...
ANNO DOMINI 1130 & 1190
The first screenshot from the year 1130 shows my capital Lisbon and the surrounding area in the Modern Age. All tiles have a mine or are irrigated and railroads are everywhere. My city pattern has some gaps that are out of reach. I know some Civ players use other patterns to maximize the use of the land but i always use the 4x4 pattern. That's how i call it when there are 4 tiles betwen the cities, so every city can make use of 20 tiles + city center.
Later in the game i always start to plant forrests in the gaps, just for the looks
I already changed my government to Social Democracy.
The second picture shows my frontline cities in (modern-day) southwest France. I was preparing for an attack on the Englisch. You can se that New Nottingham fits into my 4x4 pattern

All other cities i capture are burned down to the ground.
But while i was preparing for an attack the Koreans sent some of their troops into my land. Every Civ player knows that moment when a enemy force shows up at the border and moves into your territory. I gathered my tank armies at Aljezur. An army is a permanent stack of 2 or 3 units. Armies are very poweful and once i can build armies i do not use single units in combat anymore. The AI can make use of armies two, but seldom does so.
At the moment i have around 25 armies. Most of them still consist of 3 cavalry units.
Looking at the map, you will see that Korea is far away (Scandinavia). What i do next is: Ask Korea to remove their troops from my territory or declare war. Of course, they will declare war. Then i will destroy all their units with my armies AND drag many of the other nations into war

Sometimes the other nations need a little present like a technology or ressource to make them willing to join the fight.
When you drag other AI nations into the war it will be much easier for you. Often the enemy won't reach your territory anymore and the AI nations will battle it out somewhere. The human player just has to wait...
For example, there might be Korean Units in English territory, which the Koreans need to cross to get to my border. Now, if England declares war on Korea...
