I'm usually not crazy about real-time strategy games, as they tend to become real "click-fests" where speed is more important than actual strategy.  This one, however, has kept me interested for a few weeks  now. The technology tree is very important, as research will allow you to  create more powerful units and new buildings.  Gather resources (wood,  stone, gold, food) to build, research, expand and conquer.  The  civilizations are just different enough to keep things interesting.  Graphics and sounds are great and the scenarios are challenging.  Online  play, either competitive or cooperative, is fun.  All in all, this is a  great game with enough depth to keep Civilization fans interested.