Comparison between Civilization games

The Civilization series contains several games with many features in common. This is a brief comparison.

" in a column for an expansion pack, means that it adds nothing to the category.

Game	Civ I	Civ II	Civ III	Civ III: PTW	Civ III: Conquests	Civ IV	Civ IV: Warlords	Civ IV: BTS	CivRev	CiV	CiV: G&K
Release date	1991	1996	2001	2002	2003	2005	2006	2007	2008	2010	2012
Number of civilizations	14	21	18	26	34	16	22	32	16	18 (+7 with DLC)	26
Number of Wonders of the World	21	28	24	"	"	30	33	41	21	28 (+3 with DLC)	37
Number of Small Wonders/National Wonders	None	None	10	?	?	13	13	14	"	8	?
Government types	5	6 (introducing Fundamentalism)	5	"	"	5*5 Civics	"	"	6	5*10 Social policies	"
Number of technologies	67	89	82	?	?	?	?	?	92	47	74
Religion	Generic	Generic	Generic	"	"	Multiple identical	"	"	Generic	Generic	Multiple diverse
Espionage	Diplomats	Diplomats and Spies	Moles	"	"	Spies	"	Espionage points, Spy specialist	No	No	Espionage
Map grid	Square	Isometric square	Isometric square	"	"	Square (3D)	"	"	Square (3D)	Hexagonal (3D)	"
Resources	Bonus only	Bonus only	Bonus, Strategic & Luxury	"	"	Bonus, Strategic & Luxury	"	"	Bonus only	Bonus, Strategic & Luxury	and new resources
Unique civilization features	None	City graphics only	Unique units, qualities	"	"	Unique units, leader traits	and Unique buildings	"	Era-specific abilities	Unique units, unique buildings, unique abilities	and Unique improvements
Great People	None	None	Great leader	"	"	Artist, Engineer, Merchant, Prophet, Scientist	and Great General	and Great Spy	Artist, Builder, Explorer/Industrialist, Humanitarian, Leader, Scientist	Artist, Engineer, General, Merchant, Scientist	and Great Prophet
Hit points	None	By unit statistics	By unit experience	"	"	By unit strength	"	"	?	By unit strength	"
Other new features		Reputation	Culture, borders, war weariness, Air missions, Forced labor	Multiplayer		Health, Cottages	Vassals		Relics	City-states, national happiness, embarking, puppets