Here is the full list of all 12 Fortix achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Finish the game on Impossible difficulty.
Destroy all towers (at least 2) on a level with a single capture.
Let Xitrof lay 15 eggs on the final level, then win the level.
Complete every level to perfect on any difficulty.
Capture Xitrof.
Capture 100 dragons.
Capture 100 powerups.
Capture a catapult trigger when there is no more turret left to shoot out.
Capture one of each enemies.
Conquer at least 40% of the playfield with a single capture.
Capture a powerup while you are under the effect of an other powerup.
Capture at least 3 triggers with one capture.