Here is the full list of all 38 Okhlos achievements.
Activate 7 diferent Cryptos
Unlock all the heroes
Unlock all the entries in the encyclopaedia
Unlock all the persistent heroes and philosophers in the Agora
Unlock all the heroes that were on board the Argo
Defeat the Philosopher God
Defeat all the gods
Defeat Zeus
Beat Hades in under 25 minues
Unlock all the heroes that took part in that epic and poetic war
Heal 43 plagues
Finish 3 worlds without destroying any buildings
Unlock all the philosophers of Rapahel's painting
Perform 10 perfect blocks in a row
Defeat Dyonissus without killing any of his summons
Destroy 75 or more buildings in one world
Unlock the special ending. No more Monty Python jokes, we promise.
Defeat all the subbosses
Defeat Hades
Finish Lemnos
Break 55 smoke emitters
Finish Athens
Unlock one of the secret subbosses
Kill more than 50 enemies in the same level
Finish Atlantis
Finish Sparta
Defeat a boss with 5 or less people in the mob.
Finish Ephesos
Finish Delphi
This one is on the house. You are gonna have to work for the rest though.
Finish a world without losing any people.
Have Elektra, Oedipus and Narcissus in the mob at the same time
Defeat 100 Hecatonchires
Beat the game without using any items
Beat the game with a mob capacity of 30 or less
Finish a pacifist run
Get a mob with 50 or more phantoms in it
Unlock the statues of the twelve Olympian gods, and then break them