Here is the full list of all 25 Harvest: Massive Encounter achievements.
Established a base on Hephaestus and reached level 15 without losing any buildings.
Reached level 50 on any planet.
Reached level 100 on any planet.
Killed an alien in mid-air.
Launched an Overcharged Energy Link and killed at least 5 aliens.
Had at least 50 active harvesters at the same time in Normal game mode.
Expanded the map considerably, on any planet.
Had 20 or more active harvesters before level 11.
Killed 20 or more aliens with a single overcharged Energy Link.
Has linked 100 or more Defense Towers.
Reached level 100 on all planets.
Successfully completed the Rush game mode on any planet.
Successfully completed the Rush game mode on all planets.
Successfully completed the Wave game mode on any planet.
Successfully completed the Wave game mode on any planet in less than one hour.
Reached level 50 in the Insane game mode on all planets.
Reached level 50 in the Insane game mode on any planet.
Beat Rush game mode on any planet without losing a single building.
Accumulated 1000 or more kills with a single Defense Tower.
Expanded the map considerably, on all planets.
Had 50 or more over-heated Energy Links at the same time.
Launched all 10 waves at the same time and survived.
Defeated a wave before 15 minutes have passed.
Defeated a wave without losing a single building.
Has been awarded all other achievement awards!