Fifty years ago, Lawrence Klein began building complex econometric models of the US and UK economies. The vogue which his large scale models began eventually petered out following the Lucas critique. Today, a large scale agent-based computational economics model capable of simulating three types of agents with learning capabilities has been released. The model is massively parallel, and can simulate different types of agents, for example, households (up to $10^{7}$ ), firms (up to ∼ 10^{5}, producing consumption goods, and up to $10^{2}$ producing investment goods), and banks ( $10^{2}$).
I've been critical of ACE models in the past, but I've built a few (here, and here), read a fair amount of the literature, and I'm very interested in what might happen when we let a large scale computational model like this loose.