Teaching games is something of a art, that you'll get better at with more practise.
You're right that explaining things in certain ways can lead to more confusion that it's worth. To mitigate this I suggest explaining any in the following structure:
I recommend giving new players the simpler wonders. The gold one, the points one, or the military one are the best.
1. Thematic introduction.
"In this game, we each the ruler of an ancient city, competing to build the most glorious city the world."
Here's your chance to be creative, and have fun. You're selling the game to your friends, and setting the scene. The one important thing you're doing is telling your friends what the game is about - in this case - you're building a city.
2. Game objective, and larger game structure.
"The game is played over three ages, represented by these three decks. At the end of the third age, all points are tallied, and the person with the most points is the winner."
The important things to highlight here are:
- Winning condition. In this case earning the most points. In other games, it's the last person standing, or to go out first, for example.
- Game end condition.
3. How to achieve game objective.
The previous step immediately begs a question -
'just how do we earn points?'.
"There are several ways to earn points."
I find the best way to explain all the different ways to get points, is to go over the scoring card.
"I'll go over these quickly now, and more detail later".
Red is for military victories. At the end of each age (remember there are three), each person will battle their immediate neighbour, and the person with the highest military strength will earn points. Military strength is earned by building red cards, like this one. [Explain military points structure].
Coins. Every three coins left over at the end of the game is worth one point.
Wonders. Some of you can earn points from building your wonder. For example you can earn x points. You can earn y points.
Blues. The blue civic structures are purely for points, as denoted on the cards.
Yellows. Some yellow cards can provide points, but these tend to a be a minor bonus.
Purples. In age three is the presences of purple guilds, which give bonuses for other people are built. For example this card would...
Greens. There are green technology cards throughout the deck. [Explain green scoring. Perhaps refer to the scoring sheet to show how points are counted horizontally and vertically]. You can potentially earn a lot of points through technology - for example if you got three of each you world earn 21+ 27 = 48 points.
4. Turn structure.
"At the start of each age, we'll start with a hand of seven cards. Each turn, we'll all select a card and play it face down in front of us. Note that we all play simultaneously!
We then choose one of three actions to do with the card:
- Play it face up in front of our board, and pay the construction cost, to build that as part of a city. Note that you're only allowed to build each building once. You're not allowed two temples for example.
- Play it face down on the bottom edge of board, and pay the wonder construction cost, to build that stage of the wonder.
- Trash the card, and receive three coins. Note that if you select a card that you're unable to pay construction costs for, you're forced to trash the card.
After all the construction costs are resolved, we then pass the hand to left."
This leads well in to:
5. Construction costs
Note each card has a construction cost. For example this one here requires paying one gold into the middle, these (simple browns) have no cost, this one here requires two stone.
There are two cards that provide resources - browns and greys. Browns provide basic resources, and greys provide secondary resources. You typically only need one of each of the secondary resources.
Some yellow cards also provide resources. [Point them out].
So let's say I have these two browns providing stone already built, I can build this card because I have the required resource.
Note also - that each of us is already building one resource on our wonder card.
When building your wonder, you similarly pay construction costs, as denoted on your wonder card. Note that the Age the game is in doesn't matter for building your wonder. You can build them all in Age I or all in Age III, it doesn't matter.
Now lets say only I have one stone, but my neighbour Jim here has the other stone.
I can buy that stone from Jim for two coins. I simply put two coins on his wonder card. Note that you don't require permission to buy someone's resource and you can't stop someone buying your resources. Note also that you're only allowed to buy resources from your neighbours. Also note that my buying Jim's resource doesn't prevent Jim from also using that resource, and vice versa. Also you can only buy resources provided by browns and greys. You can't buy resources provided by yellows or wonders.
There are some cards the make the resource buying cheaper. [Point our trading posts]. "
"Some cards can be built for free, if you have build the prerequisite building. For example [who an example Age II card], this building I can either pay the construction cost of xyz, or if I have already built the [Baths/etc] then I get this building for free. Note here on the bottom right of the Baths card, that this shows me which buildings I can build for free. "
8. End of Age.
After we've played the sixth card each, the seventh card is discarded, and then we resolve military victories. The next Age we pass cards in reverse order.
9. Final notes and reminders.
- Do a quick scan over all the decks to show people what to expect. Point out the cards that give you gold for neighbour's buildings.
- You can't build the same building twice.
- You can't buy resources from the bank. You or your neighbours have to be producing it.
- You don't have to build your wonder. Treat building your wonder just like building another card.
- "If there's any cards that you're not sure what it does, just show it to me and I'll explain it."
As a final note - note that games usually seem more complicated explaining them than they are playing them. But it is best to give a comprehensive explanation upfront, and then people will usually understand it by the end of the first game.