Imagine you have few battlecruisers that don't attack and are invincible. They spawn with some pattern a certain unit you chose in the beginning until a limit of units currently alive is reached. The goal is to make the other(s) player(s) have a minimum sum of units battling to defeat him.
Evolves was a SC1 map that looks similar to this. Units would spawn underneathe Science Vessels and as you progressed in levels different units would spawn.
Are you guys describing a map that starts all players off with equal amounts of units with the map maxed, and all players spawn units continuously? Basically, the map is constantly maxed, and the goal is to kill hostiles and end up being the only player with units.