Aria is less game and more world building exercise, you start by creating a map, determining topography, seasonal cycles and weather patterns and major geological features. Then you create Heritage Groups (Species, Nations, Cultures) and then start 'play' where you are essentially playing as a Society advancing through its history and occasionally zooming in to one of its culture heroes or rulers (the closest thing to individual PC).
The mechanics were % rolls but in typical 1990s fashion they were a shambles to read through the 800-odd pages and went into excrutiating details. Luckily I was a player via PBEM so fortunately didnt have to keep checking back on every possible parameter to be rolled.
There is a fudge version which at least has easier rolls