Update: I was unfortunately not aware of Shamus Young's severe criticism of Fallout 3 available here to link in the original piece and I regret that. It dovetails rather nicely with what I've written and it's much better executed than my piece. I strongly recommend anyone...
Rome: Total War - Barbarian Invasion is the expansion to the best-selling Rome: Total War. The original game covered the rise of the Roman Empire and the struggle to be the Emperor of the Roman World. In the tradition of earlier Total War expansions, Barbarian Invasion (BI) introduces a new campaign in a time when an almost-unstoppable threat has arisen.
The expansion moves the action on 350 years to a time when the Roman Empire is in deep trouble, beset by enemies inside and out, and possibly even dying. The year is 363 AD, and the Roman Empire has split into two parts ruled from the cities of Rome (for the Western Empire) and Constantinople (for the Eastern Empire). If this weren't bad enough, barbarian tribes have been massing on the Imperial frontiers in Europe for many years. In the East the Empire faces a renewed threat from the Persian Empire, under new vigorous rulers, the Sassanids.
This is an exciting and turbulent period of Roman history: the Fall of Rome itself and the collapse of the Western Roman Empire, the slaughter of Emperor Valens and a complete Roman army at Adrianople in 378, the arrival in Europe of the terrifying Huns, the political in-fighting that saw Rome's best generals hounded as traitors, and the final humiliation of the last Emperor of the West being forced to retire in 476 AD as a barbarian took his throne. Romulus Augustulus simply wasn't enough of a threat to be worth killing.
BI starts just after the last Emperor of a unified Rome has died. His successors in Rome and Constantinople are now uneasy allies and rivals for power. The 'barbarians' are massing along the borders, and in some cases are living inside what used to be Roman territory. There are many, many challenges for a Roman to face - and some may be almost unbeatable!