Communist believers imagine a state in which everybody gets an equal share of the entire wealth of the country A key part of a communist economy is...
O following the traditions of the ancestors.
O competition between businesses.
O government ownership of all the means of production.
O businesses are private, and like monopoly you play until you go bankrupt.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.