Apocalypse strategy -
Start by building 5 Ion Cannon on top row with bunker behind each one.
Upgrade 3 Ion Cannon to level 2.
Research Economics and build one Economic center.
Upgrade 1 Ion Cannon to level 3.
Upgrade Economic Center to level 2.
Alternate between upgrading the remaining Ion Cannons to level 3 and building and upgrading another Economic center.
When you have 3 level 3 Ion Cannon research Nuclear and alternate between building missile complex and economic centers. (Always upgrade fully before starting a new building).
When you have 4 or 5 fully upgraded missile complexes you should have a decent enough income to research missile defense and planet shield.
Upgrade everything to max.
Sell off the economic centers and build more defenses.
Tip: Always have a bunker next to (not diagonally) your defensive buildings to give full protection to your population.
 "PlanetDefender"){kind=icon}