If the portfolio ever gets reopened it should have the ability for GILTs, so a bond market is created, therefore you borrow from other states which are in surplus at interest rates. When your borrowing is too large then there is the ability for sovereign default on the debt as well, if think personally this would make it a more exiciting game as you are pushed to make choices quickly and decisively.
Maybe you could think about changing the budget bit as well, with more different types of taxes like a personal allowance, basic rate and top rate for individuals then you could have corporation tax for business. At present the tax system offer very little flexibility for give away budget or targeted tax rises.
feedback would be great Smile