Here is the full list of all 77 Revenge of the Titans achievements.
Squished 50 Titans under new buildings
Defeated 4 Xmas Ultrayetis
Crushed 25 Titans under new buildings
Lost 100 buildings to the enemy
Defeated 3 Xmas Ultrayetis
Defeated 2 Xmas Ultrayetis
Defeated 1 Xmas Ultrayeti
Destroyed a Gargantuan
Completed the Mars missions
Researched all turret upgrades
Researched the decoy tower
Fully upgraded a turret
Researched the droid factory
Used the freeze powerup 5 times
Used bezerk powerup 5 times
Used the shield powerup 5 times
Repaired your buildings 5 times
Nuked 100 Titans from orbit
Nuked the site from orbit 5 times
Blew up 100 Titans using explosives
Got $10,000 in the bank
New rank: brigadier
Nuked 50 Titans from orbit
Vanquished 2,500 Titans
Researched nuclear reactors
Lost 50 buildings to the enemy
Giant Titan killed within a few metres of the base
New rank: colonel
Completed the Moon missions
Destroyed a Leviathan
Lost 25 buildings to the enemy
Vanquished 1,000 Titans
New rank: lieutenant colonel
Got $5,000 in the bank
New rank: major
Completed the Earth missions
Completed whole world at maximum difficulty
New rank: captain
Defeated a Megatitan
Vanquished 500 Titans
New rank: lieutenant
Lost 10 buildings to the enemy
Vanquished 250 Titans
Vanquished 100 Titans
New rank: second lieutenant
New rank: warrant Officer
Destroyed a Behemoth
Destroyed the Ultratitan!
Completed the Saturn missions
Completed the Titan missions
Completed all missions at maximum difficulty
Vanquished 5,000 Titans
Vanquished 10,000 Titans
Turned 100 3-D Titans into 2-D Titans
Fried 100 Titans with the Capacitor
Fried 250 Titans with the Capacitor
Fried 500 Titans with the Capacitor
Nuked 250 Titans from orbit
Blew up 250 Titans using explosives
Blew up 500 Titans using explosives
Researched all weapons
Researched all defenses
Researched all explosive tech
Researched all science and technology
Researched everything
Base held together with tape and string at end of mission
Lost 90% of your buildings to the enemy
Made $5,000 profit from one mission
Made $10,000 profit from one mission
Made $15,000 profit from one mission
Got $25,000 in the bank
Got $50,000 in the bank
New rank: major general
New rank: lieutenant general
New rank: general
New rank: field marshal
Hurrah! Christmas is finally over!