Beat the game and load your cleared saved game file to unlock New Game + mode in which you can skip the first forest part of the game and get double gold from enemies.

Survival mode:
Beat the game to unlock Survival mode. In Survival mode, the goal is to survive as many waves of enemies as possible, either with your party from the game or preset parties.

To unlock Achilles in Survival mode, beat all  117 battles in Survival mode. Start Survival mode again and choose the preset party. Achilles will be at the bottom.

Collection option:
Beat the game to display all items collected in the game and tracks the percentage of items collected. Items that are missing will have a clue to their location.

Beat the game to unlock the Records option.

Find the following statues in the corresponding loctations:

Island of Crete
Cnossus - Sorcerist Shop (Prometheus).
World map - Temple of Poseidon (Poseidon).

Laconia Outskirts
World map - Temple of Hermes (Hermes).

Sparta Outskirts
Sparta - Sorcerist Shop (Prometheus).
Sparta - Temple of Hera (Hera), located inside the city.

Mycenae Outskirts
Mycenae - Alchemist Shop (Prometheus).
World map - Temple of Demeter (Demeter).

Thessaly Outskirts
Thessaly - Sorcerist Shop (Prometheus).
Heaven's Haven Outskirts
World map - Temple of Zeus (Zeus).

Driscus Outskirts
Driscus - Sorcerist Shop (Prometheus).

Troy Outskirts
World map - Temple of Apollo (Apollo).
Troy - Sorcerist Shop (Prometheus).
World map - Temple of Ares (Ares).

Miletus Outskirts
Miletus - Sorcerist Shop (Prometheus).

Athens Outskirts
Athens - Sorcerist Shop (Prometheus)
Athens - Temple of Athena (Athena), located inside the city.

Benghazi Outskirts
Benghazi - Sorcerist Shop (Prometheus).

Atlasia Outskirts
World map - Temple of Aphrodite (Aphrodite).

Neapolis Outskirts
World map - Temple of Artemis (Artemis).
Neapolis - Sorcerist Shop (Prometheus).

Massalia Outskirts
Massalia - Sorcerist/Alchemist Shop (Prometheus).
World map - Temple of Dionysus (Dionysus).

Trantia Outskirts
World map - Temple of Hephaestus (Hephaestus)
Trantia - Sorcerist Shop (Prometheus), does not appear on map.