Not only is this mod tool a completely free content update released to every owner of a copy of Aggressors: Ancient Rome, but it's also incredibly easy to use, with a fairly streamlined process of converting an image to an actual, playable level.
Even though Aggressors: Ancient Rome has always been a fairly modder-friendly title (courtesy of Slitherine), a player's ability to mod their game has always been dependant on their ability to use various - often complicated - software suites to manipulate game files in ways that are not always obvious.
The process of using the official Map Editor for Aggressors: Ancient Rome, however, is as simple as downloading an image file for immediate conversion! Developers recommend finding an image of a physical, topographical map with as few labels as possible so that the process goes without a hitch.
Aggressors: Ancient Rome is now available via Steam for the price of €24,99, and if you're a history buff, or simply a fan of 4X games that aren't necessarily Civilisation, be sure to give it a once-over if nothing else.