Here is the full list of all 25 Interplanetary achievements.
Defeat an enemy planet.
Have your planet run out of material.
Fire all the superweapons during the same turn.
Fire Asteroid Diversion superweapon.
Fire Solar Laser superweapon.
Win an online multiplayer match.
Win an online multiplayer match with at least two players.
Win 5 online multiplayer matches.
Win 10 online multiplayer matches.
Win 50 online multiplayer matches.
Win 100 online multiplayer matches.
Win 10 single player games.
Win 100 single player games.
Beat the Impossible AI.
Win an online multiplayer match with at least four players.
Win an online multiplayer match with eight players.
Destroy 100 cities over any number of games.
Defeat two enemy planets in one turn.
Build 200 buildings on your planet.
Hit your own planet with a railgun.
Grow five cities to their maximum populations.
Win a match with barely any population left.
Unlock all technologies.
Have 25,000 material in stock.
Produce 7,000 Energy in one turn.