Barley, wheat, rye.
All the ingredients for the great scottish malts: whiskey and beer.
Add Peat as a source of energy, and throw all your ressource cubes down the cube tower. That's right: a cube tower, à la Wallenstein/Shogun.
Players will produce barrels of whiskey and beer from the 3 ingredients and ship them through Scotland.
Prices and demand will ebb and flow as the players try to amass the most money.