Although it has not a lot of things to add to Empire Earth, what Art of Conquest does offer is enough for an expansion.
The Bad: Bad looking space battles and maps, little or no improvements what so ever to things such as graphics & suffers the same problems found in Empire Earth (e.g: cheating AI, cartoon like graphics and sounds).
Before I would like to begin, I would like to tell the person reading this that the score is based from the perspective of an Empire Earth fan.
Empire Earth is one of the most enjoyable RTS games ever made. Because of the game's vast scope, it seemed that an expansion would just add new campaigns, new civilizations, new units, etc. Empire Earth fans got these in the expansion, The Art of Conquest. Firstly, the expansion has three new campaigns: Roman, Pacific, and Asian. Although two of the three campaigns are "been there, done that" campaigns, these two showcases events that were rarely depicted in other RTS games. This is especially true of the Roman Campaign. The first 3 missions is all about the highlights of the life of Gaius Marius, a Roman rarely mentioned (let alone featured) in other RTS games (in my case, the only game I so far come across this historical character is Rome: Total War). Anyway, the rest of the Roman Campaign is about the military campaigns of Julius Caesar, which was featured in a few other games. The Pacific campaign, despite its name, was basically about the Americans war against the Japanese. Of all the campaigns, this was probably the most dissapointing because all but one of the missions was featured in some other game. The campaign has some uninteresting missions (in particular the "Tooth and Nail" mission). The Pacific campaign also starts and ends abruptly (starting at the Battle of Midway and ends at the Battle of Iwo Jima, which wasn't the last battle in the Pacific during World War II). The last campaign, the Asian Campaign, is like the Russian Campaign in Empire Earth (you lead a fictional civilization to glory and all that). However, this campaign features the new Space Epoch, speaking of which...
The Space epoch lives up to its name: see space battles, conquer alien worlds and all that. Because of this new epoch, new maps, buildings and units were added to compesate although, as you'll see later, these new features for the space epoch weren't all cracked up to be.
Civilizations get an upgrade in the expansion through the new civ powers such as Expansionism, Adaptation and Camouflage. Each of course offer the owning civ certain and interesting benifits. Like all games however, Art of Conquests has a number of weak points. For one thing, although the campaigns are interesting, they all don't give you the opportunity to enhance your civilization by buying civlization bonuses. Another pitfall with this "expansion" is despite the fact that it has new units, nearly all of them aren't available in normal skirmish battles. As said earlier, the space epoch adds new units to all factions in a normal skirmish. However, besides spaceships, the expansion adds very little to land battles and absoulutely nothing to naval combat; so when you're fighting on a mostly water map during the space epoch, expect your naval units to be the same old boats used two centuries before the space epoch!
Although at first sight they look cool, space maps are nothing more than "islands separated by black water". The same goes for the space battles, which are nothing more than engagements between ugly looking boats (if you wanted epic real time space battles, better buy Star Wars: Empire at War which offers far more good looking space battles). What's probably worse of all is the fact that the developers never even improved a few features such as graphics, sound, music, diplomacy and game AI (the fact that Art of Conquest has the same old cheating AI is somewhat bizzare when you consider the fact that Mad Doc Software is a company that develops games with a very good AI).
In my review in Empire Earth, I noted the game at times wasn't serious and I think that this was greatly increased in this expansion. By creating a space epoch, the developers, IMO, exploited this to show more of the Star Wars influence on Empire Earth. Instead of creating triangular Space Capital Ships, the created a square one. The developers named one space unit "corvette" and this was a possible allusion to the Correlian Corvettes (which was, like the Art of Conquest corvette, designed to destroy space fighters) in the Star Wars universe. The main infantry unit, the watchmen, might remind players of the droids used by the Trade Federation during the Clone Wars. Even the look of the citizens have some similarities to Super Battle Droids. Besides these rip offs from Star Wars, other rip offs include the Dune Patrol unit ("inspired" by the Warthog in Halo) and the SAS commando (came from Red Alert).
Art of Conquest delivers features which a hardcore Empire Earth fan wouldn't want to miss. However, for the typical RTS fan the game's price tag of $30 seems to much for a game which is actually only less than 190 MB and has not much to offer. But since this is an expansion to a game which nearly had everything, why add so much?