The map starts with everyone choosing what level of difficulty they would like. Once everyone has chosen, a 2 minute countdown begins. During that time you can build and mine. Once the countdown is at 0 the map begins. Each player has an "X" to build on.
Here is that "X" with labels (Sorry thats hard to make out)
Blue=Water Green=Build Zone Light Green=Hero zone Purple=Enemy Path Black=Enemy flow
http://img.photobucket.com/albums/v280/Navilin/U.bmpOnce and enemy unit reaches the top right hand corner another enemy unit is spawned in the bottom right hand corner. The enemy unit is determined by what level it is. There are 5 phases of these secondary enemy units. They change every 3 levels up to level 15, with a total of 20 levels. Once level 15 is reached your hp (difficulty setting) is set to max, so all enemy units spawn with full hit points. If 10 of the phases type units reach the end then you lose (you have ten lives).
You also can buy Heros', and Special options. In addition you will recieve 1 dollar every 100 kills, with these dollars you can buy Traps, mineral, and extra drones.
That is about the just of the map.