Here is the full list of all 52 Inbound UFO achievements.
Your first kill
Win a mission by killing all enemies
Win a mission with profit
Use only the freebies to win a mission
Your first Maximum upgrade for a tower
Upgrade to Maximum all Machine Gun towers and secondary weapons
Upgrade to Maximum all Flamethrower towers and secondary weapons
Upgrade to Maximum all Freezer towers and secondary weapons
Upgrade to Maximum all Electric towers and secondary weapons
Win the same mission 20 times
Win the same mission 50 times
Win 100 missions
Win 1000 missions
Win every mission of the campaign with full homebase health
Win a mission with last enemy at less than 3m from homebase and the enemy damage would have been fatal
Win every mission once without using the Bomb Ability
Win every mission once without using the Slow Motion Ability
Reach 500,000 in game cash
Win the 20th mission
Win every mission using the Machine gun towers only
Use Slow Motion Ability 100 times
Use the Bomb Ability 1000 times
Kill 1000 enemies using the Bomb Ability
Build 1000 towers
Kill 10,000 enemies
Sell or Replace 100 towers that were destroyed at least once
Replace 20 destroyed towers during the mission
Early call last wave 50 times
Win a mission using the Electric towers only
Kill 1000 enemies with electric weapons
Early call all waves in a row on every map
Win Mission #7 using the Flamethrower towers only
Kill 100 Giants
Kill 10 times the Giant with the same tower that the Giant has disabled
Manually assign and kill one target at a time for 30 times in the same mission
Manually assign and kill one target at a time for 500 times
Kill 1000 support units: Shield Generators and Healers
Kill 50 Heroes
Kill 20 Martyrs at safe distance in such a way that they do not heal any other enemy
Kill 100 Special Ops
Kill 100 enemies with the Grenade Launcher
Kill 100 enemies with the Rocket Launcher
Kill 100 enemies with the Guided Missiles
Kill 50 enemies with E. I. Grenades
Kill 100 enemies with the Fire Jet
Kill 50 enemies with the Fire Rain
Slowdown to death 50 enemies with Nitrogen Grenades
Slowdown to death 50 enemies with the Arctic Lens
Slowdown to death 100 enemies with the Guided Blizzard
Kill 100 enemies with the Globular Lightning
Kill 100 enemies with the Electron Nest
Kill 100 enemies with the Horizon Discharge