Game play idea

I was thinking of starting a game up sometime in the near future, and was trying desperately to think of an interesting gameplay. I think I finally came up with something. I was thinking maybe an rpg/act raiser type game play. You have a world map you can walk on, but all the dungeons are set up as levels similar to act raiser. The difference is you get different people on your team. I was thinking in order to incorporate the other people (instead of just haveing the player use whomever is stronger) I would have a switch button. Where you can switch people in the middle of dungeons. Everyone you get on your team has some important feature that lets you clear the level, or kill certain enemies. Like for instance, if there is a rock golem on the screen you would have to switch to the strong sword fighter in order to kill him, or if there was a magical elemental monster, you would have to switch to the mage. You gain levels by killing monsters and such. The one thing I am debating most on, is whether or not to have different sprites and different set up for towns and villages from both the world map and the dungeon. I didn''t know if this would be something to different or not, like it wouldn''t be from the same game, or shouldn''t be from the same game. Well anyway, let me know what you guys think of my game idea, I look forward to hearing from everyone.