Here is the full list of all 11 Titanis achievements.
Beat every mission in the game.
Beat the Game.
Buy all the weapon upgrades.
Buy all the boot upgrades.
Loot 2000 gold.
Find a secret area.
Kill 500 Enemies.
Beat the giant Motocco.
Beat the giant Motocco without taking damage.
Beat Vexx without taking damage.
Do 1,000 damage to the practice dummy.