I thought at my first glance at Sierra's Empire Earth booth at E3 2000. Empire Earth, like Civilization 2, spans the history of mankind but goes even further than Sid Meier's classic into the distant future. Starting at the Stone Age, you guide your civilization through the trials and tribulations of time through seasons and over ages. You can develop technology, build wonders, customize your civilization, and make war with others from the caveman era to the distant future.
Battles take place over land, sea, and air using a variety of upgradable troops as well as heroes.
Even at this early stage Empire Earth looks intriguing and can quite possibly turn out to be one of the best civilization-building real time strategy games in the near future. Empire Earth emphasizes combat, in this regard more like AOE 2 than Civilization 2, and so provides a large number of units over land, sea, and air to make war with. Land units range from clubmen to priests to tanks to laser troopers to nuclear missile silos. From there we get more exotic, with sea units such as galleys, submarines, and warships. Ship combat is emphasized more in Empire Earth than most RTSGs so special attacks such as boarding or targeting a ships rigging is available.