Released in 2010, “Civilization V” made a lot of changes to long-established elements of the venerable strategy series.

It used hex-shaped spaces instead of squares. Only one military unit could fit on each space, rather than dozens. Religion and espionage were removed. Discrete forms of government and civics were replaced by mix-and-match social policies. Not all players liked these and other changes, but overall it was a fine entry in the series. There was room for improvement, though, and the new expansion, “Gods & Kings” (which requires the original game to play), makes a lot of them.

First off, it adds more of what was there before. There are new nations and cultures to play as, from Austria to Byzantium to Ethiopia to the Maya, each with its own historical figure, unique military unit and special building.

There are new types of Great People (prophets and admirals), new Wonders to build, new kinds of independent city-states to ally with or conquer, and several predetermined scenarios, including the decline of Rome and a Victorian- era sci-fi “steampunk” take on the game.

But the biggest additions are things that are new to “Civilization V,” but not the series — religion and espionage. Religion enters into play first — certain new buildings (and revamped old ones) generate

Faith, a new resource similar to the game’s existing Science or Culture, which allows you to gain religious buildings or figures rather than new technologies or social policies.

Amass enough Faith and you can begin worshipping a pantheon of gods, eventually founding your own religion, specifying its bonus-granting beliefs and spreading it to other cultures, which may give you an advantage in your dealings with them—especially if you choose certain beliefs, which might make your troops more effective when defending or attacking a city that shares your culture’s religion, or allow you to purchase units or buildings with Faith rather than building them or spending gold. But beware— while founding a religion provides certain benefits to you alone, other cultures that follow your faith will also enjoy some of its positive effects.

You spread religion through the use of missionaries and root out foreign belief systems with inquisitors, and though both can be a powerful influence, don’t rely on them too much — the influence of religion will taper off in time.

Once any player reaches the Renaissance era, all players gain a new resource: spies. You can’t train spies, but the ones you have get better with experience and will eventually return if captured or killed. They are able to infiltrate city-states in order to increase your influence with them, or spy on rival civilizations, steal their technologies for you and wreak other mischief. But other players have their own spies, which can do the same to you — and spies are adept at catching other agents in the act.