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