Here is the full list of all 19 Planetary Annihilation achievements.
Smash five enemy planets
Target an incoming planet with an annihilaser
Watch competitive play for two hours as a spectator
Build every structure in a single game
Build every kind of unit
Participate in ten team games
Destroy five enemy planets with annihilasers
Build every kind of basic factory
Kill a commander within five minutes, five times
Keep tabs on your conquest with ten camera anchors
Win against three times as many players
Activate an annihilaser
Manage your armies with all ten control groups
Use more than 95% of the metal and energy you produce in a match
Annihilate your opposition throughout the galaxy
Eliminate a faction in galactic war
Start a game with a custom system
Discover a new loadout in galactic war
Watch competitive play for eight hours as a spectator