Idea for completing a map with Planetary defenses

[windmill]

This idea really simple based on the difficulty set when creating a map a certain number of planetary must be place on the map before the player can ascend into space to there space station example I've created a map of medium difficulty which required 6 planetary defenses these defenses are really big guns essentially, bit like the rocket defense but they cant be placed no closer than lets say 200 tiles together. These defenses could also create a lot of pollution to add to the difficulty

The idea of this is you would be required to conquer a certain amount of land before you can ascend to space and the planetary defenses would be away of marking the land for that accomplishment creating an extra goal other than the race up the research tree

Does anyone think this would be a good idea?