Olympian
Beat game on Olympian Difficulty

If you rather not replay the whole campaign again on Olympian difficulty, you can skip right to the final boss fight with Zeus and get the achievement. I cannot take credit for finding out this glitch, I just want to pass on the knowledge on to fellow achievement hunters. Below is a video walking you through the process.

1. Beat the game on any difficulty. It doesn’t matter which (warrior or champion).
2. Once back in the main menu select continue and you will be at the final fight against Zeus.
3. After the fight loads exit to the main menu.
4. From here go to campain and then new game.
4. Select the Olympian difficulty and overwrite your original save (should say Use Slot 1).
5. Once the new game begins, load the autosave at the final fight.
6. Defeat Zeus and the achievement is yours.