About your idea of making multiple maps with varient of storms i think this should be a part of a story mode. You can make to each map one special building for example in a ice map you can make a camp fire so they don't get too cold. And after each map you can give them a bridge style based on the map and a note of the story (those you already give after winning the game). You can also make the storm a bit different for example lowering the cold of the settlers in the ice map and instead of lighting you can do something else nature do shooting ice.