Essentially similar to The Settlers AKA Serf City, Global Effect involves building up a sound local economy before going out to attack other nations and rule the world. Cities must contain housing, food sources and power supplies, which is where it gets complicated. You can choose the environmental settings of the game, in a similar way to Civilization - an icy world or a post-apocalyptic one make things much tougher.
Environmental factors play the biggest part in this game, as you have to use efficient power sources if possible. You only get a certain level of power at the start of the game, and have to build enough 'green' things to increase it further - trees are the most effective.
Once you have a fully functional city capable of supporting military units of any quality, these can be directed off into battle by giving them pre-planned flight paths which can be over-ridden if need be.
Two-player games can be played via null-modem cables, even across different systems.