Hi Malstrom,
What about a town being taken over by the Koopa Troops? Could be pretty interesting with toads running around in fear being chased by bullet bills. Maybe you could get power-ups from the toads by saving them or something. You should also be able to go into the houses by going down the chimneys, like in Zelda. Maybe the town could already have been besieged and walled, meaning you’d have to go through the sewers to gain entry and save the citizens.
There was a lot of war stuff in the early Mario games with the cannons, airships and that late stage from SMB3 with the wooden tanks (if I remember correctly) – so it’s not really a new idea entirely, but you could probably do something more with it.
As I understand it, when Koopa’s forces takes over a Mushroom world, they turn all the mushroom citizens to blocks. This is why there are so many blocks in Super Mario Brothers and why some of them have mushrooms or other items in them. At least, this is how it was explained in the original Super Mario Brothers manual. I actually had a moral dilemma when playing the original Super Mario Brothers. If broke a brick, was I killing a Toad? Apparently I was! It made the game more interesting… at least in my eyes.
The worlds of Super Mario Brothers 1 and 3 are already conquered by Bowser. You’re freeing them. Super Mario World was like a safari in a way with resistance growing the closer you got to Bowser’s new hideout. So I think the ‘conquered worlds’ has been a general theme already.