Here is the full list of all 16 Planet Explorers achievements.
Complete Escort Mission
Take over the mission The Forest
Complete the mission Bury the Dead
Complete the mission Into the Desert
Complete the mission Set up a BaseCamp
Nuclear explosion
Complete the mission Finding Malik
Complete the mission A World at War
Survive to the last minute
Collect 1000 currency
First ride on the monster
First recruitment
Collect 50 monster feces
Gain all the achievements
Destroy all the towns
Achieve Cordial in each party