It doesn't refresh the genre but it does offer a memorable play for anyone who enjoys RTS games.
Combat is similar to the previous instalments in the series, which is rather disappointing to some people. There are so many improvements made to the economic, graphical and other game play elements, that leaving the combat so similar was unexpected by many fans of the series. Many units are still shared between nations, and the cultural differences between forces are not nearly as noticeable this time around. This is probably for historical accuracy since all of the nations involved in the real colonization were European and the game still only includes those main 8 nations in the game. British, French, Dutch, Russians, Portuguese, Germans, Ottomans and Spanish. Units, instead of being unique to a civilization, are usually unique to a few civilizations instead and most nations only have 1 or 2 completely unique units while about half of your other units are shared by only a couple other nations. This gives the feeling that rather than having many unique units, you are instead being denied units that a couple of other nations are sharing. units will self-organize themselves into columns and rows while marching from one location to another, only moving as fast as the slowest unit, which is usually your cannons. However, unlike most real battles in the time period your forces do no stay in formation once battle starts. Instead of staying in position and fighting with some element of organization, all hell breaks loose and units will just get to wherever they can find and start firing as fast as they can reload. Cannons are pretty much a necessity in order to assault a base, footmen are not very efficient at taking down structures, especially ones that are being defended from within. In the end most assaults on a base will consist of cannons doing the main chunk of the work while your footmen are there mainly to protect the cannons.
Differences between the 8 nations are mainly noticeable in the economic area of the game rather than combat, with Ottomans being the main exception with their strength being some rather mean exclusive cannons and other gunpowder units. All other nations are noticeable more while building up your base. The Dutch for example put more emphasis on gold and less on food, they also have a unique gold producing building. The Spanish on the other hand, put emphasis on home city shipments and get their more quickly and with some better upgrades to buildings than other nations. Your Economy is generally the same though between the 8 nations, that is to say it's nearly identical to Age of Empires II as well. You start out with a town center and a few peasants and you start gathering resources then build up your army as you advance though the ages. Main differences from Age II is that they have eliminated stone as a resource, now only food, wood, and gold are needed to build the main units. Experience has been thrown into the mix but it's not really a typical resource as it is used and gained completely differently. Peasants also no longer have to carry back resources to a gathering building, instead they will just stay wherever they are and chop trees or mine what they are gathering right where they are without moving until the resource has been exhausted, then they move on to another if there is one nearby.
Home Cities are a unique new aspect to the series. Your home city is easily accessible at any point of the game and has many shipments of goods or units that you can send providing you have the experience necessary. Experience is gained through building units or buildings, or by destroying your opponents units and buildings. Some buildings can only be acquired through your home city, and there are many unique mercenary units that can be gained through it as well. This is probably the only way you will see any units that are not European the entire game. Most shipments are free of charge, but some (such as mercenaries) do cost resources in addition to experience to ship. Your "deck" of 20 cards is what shipments you have available during a match. You can buy new cards with your experience in-between matches. Your deck can be altered in-between matches to correspond to what kind of map your playing, such as removing naval unit cards in a map based in the Rocky Mountains.
Tilesets are widely varied and unique, with many doodads and nice touches to make them believable and enjoyable to look at. The Caribbean's waters and sand looks beautiful, while watching a fort fire cannonballs at an approaching army on the great plains is just as appealing. There are many tilesets available no matter your taste, and all of them have their own little gameplay changes and feel. Graphics are generally a great thing to see, if you have a higher end system then Age of Empires III's graphics are one of it's best features, unfortunately, if your on a more moderate system then the game can tend to bog down when in the middle of a fierce battle with the graphics set on high.
Physics are a very nice addition to the series. Rag doll effects are very nice, and it will never get old to see a musketeer take a cannonball just to go tumbling backwards and perhaps down a hill. Buildings and ships both have realistic collision physics, when a cannonball strikes a building or a ship, the area that got his will subsequently be visually damaged. a cannonball can take out the mast of a ship, or perhaps blow a massive hole in the side of your fort. Unfortunately (or fortunately) these are all just cosmetic and buildings and ships still function just fine when it appears they are held together by little more than scotch tape and and some chewing gum. This is a nice change over pelting a building with thousands of bullets or explosives just to have a little fire sprout up on the opposite site you are attacking.
The campaign is a little lacklustre and seems almost thrown in just to give you some unique scenarios to play if you don't have an active internet connection. It takes place over 3 acts with about 10 chapters in each one, give or take. You follow the story of a particular family and each act brings you to the next generation of that family while they undertake dangerous missions or searches for legendary places. Although the campaign does have it's moments, you will quickly tire of it's repetitive missions by the third act as little new is introduced as you progress through the campaign. rather than gaining access to all your units over the period of a single game as per normal, you will slowly gain access to the units in the game over the course of the entire campaign, making for little variation in what you can build through each act.
Online offers only the mode of conquest, while lacking some of the scenarios that players enjoyed in the previous instalments, such as defend to wonder. Conquest gets annoying in that you have to literally destroy absolutely everything of your enemies in order to win. So an annoying player may drag matches out by scattering peasants or buildings throughout the map, making you track down each and everyone one of them before you get the victory. Computer players are quite varied in the skills they possess, you can play computer players ranging from moronic at the "sandbox" difficultly, to quite challenging on the later difficulties. The computers are instinctively better at land combat than sea combat, although they can still pose a challenge at the later difficulties when playing on island maps.
Age of Empires III has a lot that RTS fans will enjoy even if it's unpolished. The game doesn't fill the role of redefining the genre and tends to play rather similar to it's predecessors, but if you're looking for a generic RTS game, or if you enjoyed the rest of the Age series, then you won't go wrong by picking yourself up a copy of this game.