Here is the full list of all 28 Planet Modular TD achievements.
Kill 100 enemies
Kill 1000 enemies
Complete the human planet
Complete the insectoids planet
Complete the fargos planet
Improve module
Change proposed upgrades
Unlock all modules
Discover all combinations
Upgrade destabilized tower 5 times
Build 20 orbital towers (any type)
Build 20 drones towers (any type)
Make the combo
Build 20 laser towers (any type)
Kill 100 enemies by flamethrower
Upgrade the tower
Read the encyclopedia
Build "Tesla 2.0" tower
Use the power amplifier
Use 10 skills
Get level 6 module
Atomize 10 modules
Complete level without souls lost
Get 1000 energy from "economy" modules
Stabilize the module
Win the level with left 1000 energy
Unlock all achievements