What
Empire Earth may lack in presentation, however, it makes up for in gameplay. For sheer scale, it's completely untouched in the RTS genre, and while it may seem like a direct riff on
Age of Empires II, it's different enough and complex enough to win converts from that camp.
The game spans what amounts to all of human history, albeit with gaps here and there; you'll find yourself starting off in prehistory, progressing through the Stone Age, Bronze Age and the like, coming up through ancient Greece, and eventually finding your way to the 20th century and beyond. This gigantic time span, from prehistory to the Nano Age, is divided into Epochs. Like in Age of Empires II, you progress from Epoch to Epoch by spending certain amounts of resources. New Epochs bring new units, which are often completely devastating when used against civilizations behind the development curve.
In fact, many of the concepts in the game may seem directly taken from the Age of Empires line. Many of the resources--food, wood, and the like--are directly from it, as are the methods of retrieving those resources. This causes an amusing incongruity as you get further into the game; it's funny farming a fish shoal in the Nano Age. Nonetheless, weird 'time' issues aside, the core mechanics of the 'economy' are so tried and true that it's no surprise that Empire Earth feels like it got it right.
The game also sports different civilizations to choose. The difference between the civilizations is more like the differences in Civilization or the SimTex games than those in Age of Empires--each civilization has a number of strengths, and you can even create your own custom civilizations with their own particular strengths. These can be civ-spanning, such as quicker peasants and the like, or they can be geared towards a specific age--stronger tanks, faster cavalry, what have you.
What's more interesting is the way that the units themselves work. In a given age, units have a sort of 'rock-paper-scissors' relation. Unit X may be strong against Unit Y, but it's weak against Unit Z. Sometimes the choices of these are sensible, sometimes they're fairly arbitrary, but whether they make logical sense to you or not they're key to becoming really good at the game. Using your units against those which they fight well and keeping them away from the ones that damage them is an important part of any strategy.
There's much more here, of course. The game sports a number of different campaigns, each taking you through a particular period of time. They're fairly heavily scripted, and often quite challenging. It also sports a training campaign which is meant to get you used to the game's controls; veterans of the Age of Empires games probably won't need it. During the campaigns, you can gain civilization points, which you can spend on more abilities for your people. It's a nice touch, and it makes it feel like you're really accomplishing something when you gain those points.
Where the game really shines is the random and multiplayer options. You can make maps ranging from tiny to absolutely enormous, set their features, set the number of civilizations on it and the distribution of the resources of the like. Perhaps most importantly, you can choose how many epochs you want to play through. There's pretty much no way you can play through the entire span of Empire Earth in a single setting, unless you can go without sleep for a few days; thankfully, the game doesn't force you to do that. It even has 'tournament' settings, which basically make the game more dynamic, with quicker jumps in epochs and weaker structures.