I decided to forsake a complicated story and instead go with a game that is more strategy, economic.
The game will have the goal of going from from A to B through a series of missions, M1-Mx. User will be able choose the order of the missions that is best for their status (loadout, defense etc). The hard part is finding a challenging and engaging balance.
Something like:
(AttackerPower+AttackerDefense) - (YourPower+YourDefense) = Difficulty
Then place an expectation of user power+defense to be at particular levels having completed x number of missions.
Plus, I need a UI and reward system that keeps drawing players forward.