Ruma is a Powered by the Apocalypse game about a Roman Empire that is facing off against supernatural threats summoned by it barbarian neighbours. Players take the role of characters who are confronting those threats.
The rules introduce Latin-flavoured playbooks that reflect various roles in historical Roman society and within the Legions.
Irritatingly Ruma introduces some alternative names and spellings for the various countries and peoples of its world. It tries to put some fictional distance from history but not in a way that adds to the historical roots. While flawed as a narrative campaign Hunters of Alexandria did a better job of blending the historic and supernatural fantasy of its world.
Apocalypse World, as a ruleset, seems appropriate to the environment, the Empire is powerful but besieged by threats that seek to overthrow it. Characters will win big eventually but the costs will be high.
Ruma's fundamental problem for me is that I'm not sure why this isn't a skin for Monster of the Week. You play in a group, threats emerge and need to be countered.
Ruma is also badly in need of some good Threats and Fronts in the style of DungeonWorld. There's no real need to explain what has happened to the world (no-one explains the Apocalypse in Apocalypse World after all) instead it requires a compelling and urgent threat to the Roman way of life that needs to be met right now and only the characters can step up to the challenge.
What the book provides feels like a fundamental misunderstanding of the whole concept. In one of the suggestions a rich Roman needs the characters to recover lost knowledge from a foreign ruin, the escalations feel more like steps in a scenario and the final outcome of the threat is crop failure in Rome. Joe Banner's work (such as the recent Bastion Ein Sof) would be an ideal template here.
I really like the idea of Ruma but this is not an execution that does justice to the conceit.