For the Civilopedia entry on the Sumerians, click here.
Between the Tigris and the Euphrates arose the Sumerians. In this ancient land they were the 1st among many to use the Tigris and the Euphrates for agricultural purposes and invented the worlds 1st alphabet.
In the game the Sumerians are Agricultural and Scientific. This trait combo is a paradise for the builder civ player. Right off the bat the Sumerians can build granaries to get a settler factory going early on. A decent start with a river and bonus food resources gets the Sumerians off to a fast start perhaps more pronounced than any other civ in the game. If they can trade for Alphabet early on the Sumerians are well placed to research Writing and Philosophy to grab Literacy for free. Even if you have no intention of building the Great Library, half priced normal libraries are tempting for the builder player. Sumeria is one of the best civs in the game for culture with cheap Libraries, Universities and Research Labs and usually a large population as well. Throw in cheap aqueducts and you should have some of the largest cities in the game before most of the AI civs. Sumeria is one civ the AI seems to be able to play reasonably well.
Enkidu Warrior: The Sumerian UU is the Enkidu Warrior. Basically a half priced 10-shield spearmen with stats of 1-2-1 (that replaces both warriors and spears) they can build straight away without any resources needed. You get an excellent defender early in the game for a mere 10 shields. Although the Sumers may struggle in an early offensive they are second to none on the defensive. Even the mighty Greek Hoplite can’t compare to the cost efficiency of the Enkidu Warrior. For every hoplite or spearmen you can build the Sumerians can build 2 Enkidu Warriors. Generally, 2-3 Enkidu Warriors should defend every Sumerian city. Any AI that attacks has to plow through each city, while it’s easy for the Sumerian player to rush reinforcements to the front. By using the terrain properly you can easily trade a 10 shield EW for a 30 shield swordsmen or even a medieval infantry or knight. Sumeria wins its early wars with attrition strategy the AI can’t afford to pay. Sumerian cities are often productive as well, as its not an issue to use 2-3 Enkidu as military police and still have a large mobile army in the field. The only drawback is the unit support (Sumeria has a lot of units), the 60 gold required to upgrade them to a pikes and Sumeria can’t build normal warriors. A mass upgrade from warriors to swordsmen is unlikely with the Sumers.
For the pure warmonger Sumeria doesn’t offer as much as the other civs. If you don’t mind an early golden age you can try an Enkidu Warrior rush generally after you have researched Iron Working or Warrior Code. With the Enkidu Warrior triggering a GA you can flood a nearby AI civ and pillage their improvements and steal their workers. The GA will also let you build archers or swordsmen quickly if you have access to Iron. Personally I prefer a late ancient age GA with Sumeria, as there’s a snowball effect from being able to build marketplaces, libraries, and a massive army along with the free tech you receive from the scientific trait at the start of each new age. Sumeria should have a well-developed infrastructure and large army by then. Few AI civs can stand up to an Enkidu Warrior/Pike army with catapult support at this point of the game.
Once Sumeria gets going after the early defensive or expansion wars you are well placed for the rest of the game. In the late game Sumeria is ideal for a space race victory or perhaps a cultural victory. Even for the warmonger an advanced, large Sumeria can provide an easy conquest or domination win. The Agricultural trait still provides a late game boost with cheap hospitals and recycling centers and the amount of science Sumeria can produce is impressive. If an AI Sumeria is in the late game, it is probably either in the tech lead or near to it, and will probably be one of the hardest AI civs to beat.
Summary:
The Sumerians are one of the easiest civs to play. For the new player it offers rapid growth and science with an excellent UU to keep you alive. For the advanced player you get a nice trait combo and an ultra cheap defensive UU to help survive the insanity of deity level games. Although there are better civs in the game for culture and warfare Sumeria has few if any weak points compared to the other civs. The main negative is the trait combo- great traits individually but little synergy between the two. They are a 1st tier culture/builder civ, and are towards the top end of the 2nd tier warmonger civs due to the power of its UU. Sumeria isn’t really map dependent except on island maps and even then they’re no worse off than any other non-seafaring civ. Overall I would rate them as a high 2nd tier civ.
Ision’s comment: I agree with Zards listing of the Sumers as an overall 2nd tier Civ.