One of the best games ever made. It has dozens of hours of fun waiting for you!
In a custom game you can choose a variety of different options before the start of a game. You can choose how many enemies, what civilization they are, whether or not there will be random events, whether or not there will be barbarians, etc. You also give guidelines about what kind of world you want: many islands, only one continent, jungle, and everything in between. You are also allowed to choose victory conditions: eliminate all enemies, have highest culture, have the most points, good old fashioned space race, etc. You must also pick a leader. This will give you different bonuses; some give money bonuses, improvements to military, better culture, and many others.
EARLY GAME (0~5 hours)
At first, you need to explore and build cities. Every unit is important, and new cities drastically change your empire. Workers can transform the wilderness into productive new land. Because custom games are random maps, there is a ton of variability. You try to quickly find important resources (sheep, copper, stone, wheat, fish, etc.) to reap the benefits. Each square gives food, production, and/or commerce. Commerce is the most versatile, and can be used to get gold, research power, expand your cultural influence, or spy power. This is my favorite part of the game. Planning your city placements, improving them, and watching your empire expand is a lot of fun. There is a lot of good strategy about where to put cities, how to maximize the number of cities in your area, and balance the cost of your actions. This sets up the rest of the game, will you focus on commerce (research/money) or production (building speed)?
MID-GAME (5~15 hours)
At this stage of the game, your expanding into new territories is done. You have either filled your island or met up with the other members of your continent. Now you focus on technology. It is a lot of fun to choose what you will research. You must decide If you manage to get ahead of your neighbor on research, you can use advanced units to take him out. You also must build different buildings in all your cities. These keep your cities healthy or happy, improve production, get you more money, etc. You must also fight to quickly build wonders. World wonders can only be built by one civilization, and come with large benefits to that city or your entire empire. This is where the game can be fun with regard to warfare. If you plan well and have a strong empire you can roll on your rivals with guns while they come back with axes.
END GAME (15+ hours)
By now, all (or almost all) of the technology is researched and any weak civilizations have been taken out. This is the only part of the game that can become boring. Taking over cities by brute force (where the units are equal level) is a slow process. While all other parts of the game are very well balanced and require thought, warfare is strangely simple. You build units and send them into battle. That's pretty much it. You can spice things up with airplanes, but there is no real strategy in the fighting. With nation building over, all you can do is build units and send them off, build units and send them off, build units and blah them blah. This has been aided slightly by expansion packs, but I will not get into that here.
TO WRAP UP
Civilization 4 is a great addition to the series and a great addition to video games period. The range of game experiences you can have after multiple plays is astounding. Your tenth game is as fun and engaging as your first. Deep, thought provoking choices will keep you interested, and coming back! It offers hours and hours of strategic gameplay that will have you saying the famous phrase "just one more turn…".