One of the things about a free market is that it functions
cyclically. In other words there are periods of expansion and contraction.
While, we are all familiar with THE great depression starting in 1929 (of which there are many factors, the above being only a very brief summary of causes),
recessions are common. There were also as were
other depressions before the great depression; particularly noteworthy was the long depression of the late 1800s.
My suggestions:
1) Depressions are worldwide. Its fine that a depression affects stability in other countries. But I think the effect should be virtually universal. Everyone should be affected simultaneously. We shouldn't see one country have a great depression which affects other countries, and then 5 turns later, another country have the great depression.
2) Other economic systems should be hit too, Mecantilism especially so. Arguably one of the causes of the depression leading to the war of 1812 was the US adopting a more isolationist (mercantile?) trading strategy due to the war in Europe. Communism shouldn't make you completely immune.
However, it should have a
substantially weaker effect on communist countries.
3) Depressions should maybe affect countries that have discovered Corporation, and not be linked exclusively to free markets. This would help represent how some counties could be isolated, or not yet industrialized. I think the economic cycle is more tied to the industrial revolution than to just having a free market.
4) Even free markets should be able to adopt controls. While the US is not completely a free market, its arguably as close a working model as we have. There are numerous controls that exist to blunt the effect of the economic cycles (e.g., federal reserve, insured bank deposits, etc). Hypothetically, this has mad us immune since the great depression, but then, the most severe depression cycles seem to be 50-80 years, so we don't really know yet, do we?
5) They should be less frequent. There have been numerous recessions, but depressions are very few and far between. Depending on exactly how you define them, there have been 3 in the last 200 years. I don't know offhand the length of time between depressions in the game, but it seems to happen a lot. Maybe this is just because they are not globally linked, but rather work like dominoes in the game. Still, I think they should be modeled more like the plague, and about as frequent.