Your link doesn't work, had to go through your profile. When it comes to development a good rule of thumb is to focus on the core gameplay loop first, before thinking about adding additional content. So as long as you have a basic setup of characters thus far, that means adding things like tunnels/dungeon's, more playable characters, more level's, difficulties, or a story mode, etc. would be premature.
Focus on things like the skill tree, level system, money system, character select screen (if you already have enough characters) so you can add to it later, commanding allies, 3rd/first person view, etc. In other words, focus on fleshing out what you CAN DO before adding more things TO DO. Assuming story mode has a story, that should probably come last once all your gameplay elements, characters, and maps are implemented.