When you start the game, you’ll get to choose your main hero, Rowan or Lianna. The selection is permanent and doesn’t have any major effect in the gameplay and story, except who of the two will be “locked” or become as the required character in a particular Map. Later in the story, the other sibling will become unlocked as a playable character.
Next, you’ll get to choose the difficulty. The difficulty can be changed in-game right before starting a mission. It’s recommended to stick with Hard mode when repeating maps in order to get the most out of EXP and money gain. (Hard has x1.5 gold multiplier at the end of the mission) It is recommended to try the missions immediately in Hard since the difficulty curve of the game especially in Story missions isn’t that steep.
Casual - Fallen allies return automatically in the next chapter
Classic - Fallen allies will not return in the next chapter. You can still revive them via the Temple option in the Camp Menu, a feature that will be unlocked later in the game.
Slow and Steady - Notifications and guides will appear in your screen often like level-up stats, mission briefings, and guide windows. I suggest leaving this on if you’re playing the game for the first time.
Quick and Efficient - This turns off level-up windows and mission briefs. You’ll still get important guides. Select this option if you’re already familiar with the game mechanics or if you’re replaying the game from start.