Imperator + Metropolis mod is base on an beta Imperator Final Edition + metropolis mod (not sure really which version). The challenge is more in the strategic sense due to features of metrpolis mod which makes population grow very slow. Honestly I never played the combined mod yet because I myself is enjoying my current campaign which took an expected turn. Pyrhhus is still alive in 265 BC with only Syracuse left as a Greek province. He still have a full stack in Italian mainland but is my ally.
I need that because the Gallic tribes in the north seems to get nasty and started their incursion down south. I do not need 2 front war.