The Grand Saga
Characters created for this setting should be indicative of Norse Ideology, not in equipment, but in behavior, worship (they use the Asgardian Pantheon), and values.
Characters will want to be wary about using excess amounts of fire. While creatures in the region are much more likely to be susceptible to fire, the environment will be as well. This means that a misplaced (or well placed, depending on your outlook) fireball could cause an avalanche, cave in, or even melt the surface of a frozen lake.
Characters from this setting should be EXTREMELY careful about conspiring with dragons or utilizing ANY power or ability that might be reminiscent of a draconic nature. Being suspected of consorting with dragons will draw the ire of every non-chaotic, non-evil member of your civilization, to the point that they will most likely initiate “mob justice” before you make it to trial.