I'm still trying to figure out what the 'house rules' options in Itadaki Street DS are (because they're all in Japanese :(). I have already discovered that the first option changes how the turn order is decided (via the numerical slots or fixed) and the second option is the value a player needs to reach to win the game.

After starting the game with the last option changed to the second setting, I find a lot of empty land (with the SALE sign) in places where there used to be a shop, so that there is one in each area (colour group).

The settings are, from left to right: normal, one empty land block in each area, two empty land blocks in each area and every space becomes empty land.

Contributions on the game's forum board would probably be appreciated, if anyone is reading this who knows what those settings do.