A really good idea, good effort, but just short of the finish line.
The fact that it has 12 eras to play in which is really fun because you can practically transition from any RTS era to another (even sci-fi fantasy which is in the later ages). They finally put controllable airplanes in a major RTS game which is good because I love my squadron of bombers. Fighting in the modern era is really cool too because it makes you understand modern war tactics. Aircraft carriers are fun as well, but are sadly still disproportionate to other things on the map. For example a villager is as big as tall as a tank and an airplane is the size of a horseman. But the game is fun non-theless, it possesses a 3d landscape that you can zoom into during the game (there is really no reason for this but they added it to the game and its fun to use ocassionally). Having a hero in the game is fun too except for the fact that you have to trigger his abilities, its not automatic like in Warcraft III. Watching the midieval armies fight is fun too, and I like the buildings they drew for that age/era, they are authentic looking. Having snipers is cool too, thought it would be nicer if they laid down. Lastly the WW2 artillary is awesome! Sadly there is only one artillary unit, but you can supplement that with airplanes.
The editor is good in this one too, you can practically make your own detailed campaigns and movies! Yeah you can actually make those in-game movies you see in all the RTS games, though it is rather hard to learn with all the triggers and all.
The transition from era to era is really sketchy which makes sense because human techonology changed so drastically so its makes sense. But I do recall that the Roman legions were more powerfull than the barbarians and that doesn't really happen in the game. The lack of more units makes it kind of annoying to because you want to totally experience an Era/Age when your playing and you only get a glimpse of it before you advance and go to the next. Eventhough there is a variety of units to play with in Singly player, in multiplayer everyone has the same units (there are no set civilizations with their own units). Although there are civiilizations in a sense, you have a 100 bonus to spend on your custom civilization and give your people special advantages like faster villagers or faster airplanes. Or you can pick from the preset civs which is just preset bonuses not really the civ (although it does almost match the people's military tendancies but that is irrelevant, because people would have better planes not the same planes that are faster!). Anyway, single player levels are really long and somewhat boring. The future ages make no sense with walking robots because it would be way more efficient to have the have wheels or fly and its hard to distinguish between them because its just an army of shooting robots (except one with a sword). The first ages are really useless too, fighting in the prehistoric age is really bland because there are only 3 land units to pick from, and a raft with a guy hurling rocks. They could have been more creative then that really! Oh, and what's up with only six people to a mine? I wanna mine gold damnit! Other things that are missing is cruise missiles which I really wanted to use, missile silos in multiplayer, more helicopters, any sort of long range missile too (scud for example), being able to alter the landscape with your army would also be a really positive revolutionary step which would have made this game really good (imagine being able to make bridges or ditches).
The Bottom Line
Well to tell you the truth I was going to get a job at SSS and I talked to Rick Goodman the head of the company and he told me his dreams and aspirations for Empire Earth. To tell you the truth the ideas in his head sounded like a splendid game, but I think when they actually made it, it fell short of his invisioned glory. Maybe with better artists and more production time they could have made it a really good game. But the sad reality is that Empire Earth gets boring pretty fast, after you've seen all the eras and have gotten frustrated trying to figure out how to advance (which I still don't exactly understand 'til this day) because there is either a need for another town center or building or more military units and its not written down in the manual either. Also the multiplayer can only go so far. It's too rigid in my opinion and winning in the modern age is easy. Make some anti tank guns and a huge group of bombers and bomb everything the enemy has. Add one or two B-2's and you've got yourself a win almost guarenteed (that is unless the other guy hasn't done that to you first).
If you want good strategy games that came out the same time as this one that are better you should check out Warcraft III which is very good, or Age of Mythology which is good.